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Sample records for ae star hd163296

  1. The Herbig Ae Star HD 163296 in X-Rays

    Science.gov (United States)

    Swartz, Douglas A.; Drake, Jeremy J.; Elsner, Ronald F.; Ghosh, Kajal K.; Grady, Carol A.; Wassell, Edward

    2004-01-01

    Chandra X-ray imaging spectroscopy of the nearby Herbig Ae star HD 163296 at 100 AU angular resolution is reported. A point-like, soft (kT approximately 0.5 approximately kev), emission-line source is detected at the location of the star with an X-ray luminosity of 4.0e29 erg/s. In addition, faint emission along the direction of a previously-detected Ly-alpha-emitting jet and Herbig-Haro outflow may be present. The relatively low luminosity, lack of a hard spectral component, and absence of strong X-ray variability in HD 163296 can be explained as originating from optically-thin shock-heated gas accreting onto the stellar surface along magnetic field lines. This would require a (dipole) magnetic field strength at the surface of HD 163296 of at least approximately 100 approximately G and perhaps as high as several kG.

  2. The Herbig Ae star HD 163296 in X-rays

    CERN Document Server

    Swartz, D A; Elsner, R F; Ghosh, K K; Grady, C A; Wassell, E; Woodgate, B E; Kimble, R A; Swartz, Douglas A.; Drake, Jeremy J.; Elsner, Ronald F.; Ghosh, Kajal K.; Grady, Carol A.; Wassell, Edward; Woodgate, Bruce E.; Kimble, Randy A.

    2005-01-01

    Chandra X-ray imaging spectroscopy of the nearby Herbig Ae star HD 163296 at 100 AU angular resolution is reported. A point-like, soft (kT~0.5 keV), emission-line source is detected at the location of the star with an X-ray luminosity of 4.0e29 erg/s. In addition, faint emission along the direction of a previously-detected Ly-alpha-emitting jet and Herbig-Haro outflow may be present. The relatively low luminosity, lack of a hard spectral component, and absence of strong X-ray variability in HD 163296 can be explained as originating from optically-thin shock-heated gas accreting onto the stellar surface along magnetic field lines. This would require a (dipole) magnetic field strength at the surface of HD 163296 of at least ~100 G and perhaps as high as several kG. HD 163296 joins the T Tauri star TW Hya in being the only examples known to date of pre-main-sequence stars whose quiescent X-ray emission appears to be completely dominated by accretion.

  3. Active phenomena in the pre-main sequence Herbig Ae star HD 163296

    Science.gov (United States)

    Catala, C.; Praderie, F.; Simon, T.; Talavera, A.; The, P. S.

    1989-01-01

    Observations by IUE of the short-term variability of the Mg II and Ca II resonance lines in the Herbig Ae star HD 163296 are presented. Evidence that these lines show a phenomenon of rotational modulation, similar to the one observed in AB Aur, another Herbig Ae star is found. The variations in the spectrum of HD 163296 are even more conspicuous than in the spectrum of AB Aur. Magnetically structured winds may thus be a widespread phenomenon among the pre-main sequence Herbig Ae/Be stars.

  4. Radio continuum observations of the Herbig Ae/Be stars HD 163296 and HR 5999

    Science.gov (United States)

    Brown, D. A.; Perez, M. R.; Yusef-Zadeh, F.

    1993-01-01

    Very Large Array (VLA) observations of the two bright Herbig Ae/Be stars HD 163296 and HR 5999 have been carried out at lambda 3.6 and 20 cm. We report the detection of a radio source at lambda 3.6 cm that may be associated with HD 163296. From the peak flux density of 0.39 mJy/beam area, we estimate a mass-loss rate of 1.8 x 10(exp -8) solar mass/yr if the flux is due to free-free emission in an ionized wind with spherical symmetry, assuming a terminal wind velocity of 200 km/s. HR 5999 was not detected at either wavelength. We discuss the results in terms of the stellar-driven and accretion-driven scenarios for line and wind formation in Herbig Ae/Be stars.

  5. Relating jet structure to photometric variability: the Herbig Ae star HD 163296

    CERN Document Server

    Ellerbroek, L E; Dougados, C; Cabrit, S; Sitko, M L; Sana, H; Kaper, L; de Koter, A; Klaassen, P D; Mulders, G D; Mendigutia, I; Grady, C A; Grankin, K; van Winckel, H; Bacciotti, F; Russell, R W; Lynch, D K; Hammel, H B; Beerman, L C; Day, A N; Huelsman, D M; Werren, C; Henden, A; Grindlay, J

    2014-01-01

    Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the outflow history. We present the first optical to near-infrared (NIR) VLT/X-shooter spectra of the jet from the Herbig Ae star HD 163296. We determine physical conditions in the knots, as well as their kinematic "launch epochs". Knots are formed simultaneously on either side of the disk, with a regular interval of ~16 yr. The velocity dispersion versus jet velocity and the energy input are comparable in both lobes. However, the mass loss rate, velocity, and shock conditions are asymmetric. We find Mjet/Macc ~ 0.01-0.1, consistent with magneto-centrifugal jet launching models. No evidence for dust is found in the high-velocity jet, suggesting it is launched within the sublimation radius (<0.5 au). The jet inclination...

  6. Relating jet structure to photometric variability: the Herbig Ae star HD 163296

    NARCIS (Netherlands)

    L.E. Ellerbroek; L. Podio; C. Dougados; S. Cabrit; M.L. Sitko; H. Sana; L. Kaper; A. de Koter; P.D. Klaassen; G.D. Mulders; I. Mendigutía; C.A. Grady; K. Grankin; H. van Winckel; F. Bacciotti; R.W. Russell; D.K. Lynch; H.B. Hammel; L.C. Beerman; A.N. Day; D.M. Huelsman; C. Werren; A. Henden; J. Grindlay

    2014-01-01

    Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the out

  7. Strong near-infrared emission in the sub-AU disk of the Herbig Ae star HD163296: evidence for refractory dust?

    CERN Document Server

    Benisty, M; Isella, A; Berger, J-P; Massi, F; LeBouquin, J-B; Merand, A; Duvert, G; Kraus, S; Malbet, F; Olofsson, J; Robbe-Dubois, S; Testi, L; Vannier, M; Weigelt, G

    2009-01-01

    We present new long-baseline spectro-interferometric observations of the HerbigAe star HD163296 obtained in the H and K bands with the AMBER instrument at VLTI. The observations cover a range of spatial resolutions between 3 and 12 milli-arcseconds, with a spectral resolution of ~30. With a total of 1481 visibilities and 432 closure phases, they result in the best (u,v) coverage achieved on a young star so far. The circumstellar material is resolved at the sub-AU spatial scale and closure phase measurements indicate a small but significant deviation from point-symmetry. We discuss the results assuming that the near-infrared excess in HD163296 is dominated by the emission of a circumstellar disk. A successful fit to the spectral energy distribution, near-infrared visibilities and closure phases is found with a model where a dominant contribution to the H and K band emissions arises from an optically thin, smooth and point-symmetric region extending from about 0.1 to 0.45 AU. At the latter distance from the sta...

  8. Warm H2O and OH in the disk around the Herbig star HD 163296

    CERN Document Server

    Fedele, D; van Dishoeck, E F; Herczeg, G J; Evans, N J; Bouwman, J; Henning, Th; Green, J

    2012-01-01

    We present observations of far-infrared (50-200 micron) OH and H2O emission of the disk around the Herbig Ae star HD 163296 obtained with Herschel/PACS in the context of the DIGIT key program. In addition to strong [OI] emission, a number of OH doublets and a few weak highly excited lines of H2O are detected. The presence of warm H2O in this Herbig disk is confirmed by a line stacking analysis, enabled by the full PACS spectral scan, and by lines seen in Spitzer data. The line fluxes are analyzed using an LTE slab model including line opacity. The water column density is 10^14 - 10^15 cm^-2, and the excitation temperature is 200-300 K implying warm gas with a density n > 10^5 cm^-3. For OH we find a column density of 10^14 - 2x10^15 cm^-2 and T_ex ~ 300-500 K. For both species we find an emitting region of r ~ 15-20 AU from the star. We argue that the molecular emission arises from the protoplanetary disk rather than from an outflow. This far-infrared detection of both H2O and OH contrasts with near- and mid-...

  9. ALMA detection of the rotating molecular disk wind drom the young star HD 163296

    CERN Document Server

    Klaassen, P D; Mathews, G S; De Gregorio-Monsalvo, J C Mottram I; van Dishoeck, E F; Takahashi, S; Akiyama, E; Chapillon, E; Espada, D; Hales, A; Hogerheijde, M R; Rawlings, M; Schmalzl, M; Testi, L

    2013-01-01

    Disk winds have been postulated as a mechanism for angular momentum release in protostellar systems for decades. HD 163296 is a Herbig Ae star surrounded by a disk and has been shown to host a series of HH knots (HH 409) with bow shocks associated with the farthest knots. Here we present ALMA Science Verification data of CO J=2-1 and J=3-2 emission which are spatially coincident with the blue shifted jet of HH knots, and offset from the disk by -18.6 km/s. The emission has a double corkscrew morphology and extends more than 10" from the disk with embedded emission clumps coincident with jet knots. We interpret this double corkscrew as emission from material in a molecular disk wind, and that the compact emission near the jet knots is being heated by the jet which is moving at much higher velocities. We show that the J=3-2 emission is likely heavily filtered by the interferometer, but the J=2-1 emission suffers less due to the larger beam and measurable angular scales. Excitation analysis suggests temperatures...

  10. Gas modelling in the disc of HD 163296

    CERN Document Server

    Tilling, I; Meeus, G; Mora, A; Montesinos, B; Riviere-Marichalar, P; Eiroa, C; Thi, W -F; Isella, A; Roberge, A; Martin-Zaidi, C; Kamp, I; Pinte, C; Sandell, G; Vacca, W D; Ménard, F; Mendigutía, I; Duchêne, G; Dent, W R F; Aresu, G; Meijerink, R; Spaans, M

    2011-01-01

    We present detailed model fits to observations of the disc around the Herbig Ae star HD 163296. This well-studied object has an age of ~ 4 Myr, with evidence of a circumstellar disc extending out to ~ 540AU. We use the radiation thermo-chemical disc code ProDiMo to model the gas and dust in the circumstellar disc of HD 163296, and attempt to determine the disc properties by fitting to observational line and continuum data. These include new Herschel/PACS observations obtained as part of the open-time key program GASPS (Gas in Protoplanetary Systems), consisting of a detection of the [OI]63mic line and upper limits for several other far infrared lines. We complement this with continuum data and ground-based observations of the 12CO 3-2, 2-1 and 13CO J=1-0 line transitions, as well as the H2 S(1) transition. We explore the effects of stellar ultraviolet variability and dust settling on the line emission, and on the derived disc properties. Our fitting efforts lead to derived gas/dust ratios in the range 9-100, ...

  11. Shadows and cavities in protoplanetary disks: HD163296, HD141569A, and HD150193A in polarized light

    CERN Document Server

    Garufi, Antonio; Schmid, Hans Martin; Avenhaus, Henning; Buenzli, Esther; Wolf, Sebastian

    2014-01-01

    The morphological evolution of dusty disks around young (few Myr-old) stars is pivotal to better understand planet formation. Since both dust grains and the global disk geometry evolve on short timescale, high-resolution imaging of a sample of objects may provide important hints towards such an evolution. We enlarge the sample of protoplanetary disks imaged in polarized light with high-resolution by observing the Herbig Ae/Be stars HD163296, HD141569A, and HD150193A. We integrate our data with previous datasets to paint a larger picture of their morphology. We report a weak detection of the disk around HD163296 in both H and Ks band. The disk is resolved as a broken ring structure with a significan surface brightness drop inward of 0.6 arcsec. No sign of extended polarized emission is detected from the disk around HD141569A and HD150193A. We propose that the absence of scattered light in the inner 0.6 arcsec around HD163296 and the non-detection of the disk around HD150193A may be due to similar geometric fac...

  12. Diagnosing the Structure of the HD 163296 Protoplanetary Disk Via Coronagraphic Imaging Polarimetry

    Science.gov (United States)

    Kowalski, Adam F.; Wisniewski, John P.; Clampin, M.; Grady, C. A.; Sitko, M. L.; Bjorkman, K. S.; Fukagawa, M.; Hines, D. C.; Katoh, E.; Whitney, B. A.

    2008-01-01

    Coronagraphic imaging polarimetry is a high contrast imaging technique which can diagnose both the spatial distribution and size distribution of dust grains which comprise primordial protoplanetary disks. It can therefore be a useful tool to test our understanding of how the structure of young disks evolves through the era of gas giant planet formation. We report our initial analysis of the H-band polarized and total intensity of the nearby Herbig Ae star HD 163296, and characterize the morphology of the scattered light disk in the context of previous optical HST coronagraphic imagery. Our observations were obtained as part of a multi-epoch campaign designed to diagnose and correlate the behavior of the inner and outer regions of select protoplanetary disks. This campaign will help test recent suggestions (Sitko et al. 2008; Wisniewski et al. 2008) that that HD 163296 dis experiences the novel phenomenon of time-variable self-shadowing, whereby occasional changes in the scale height of the inner disk wall induces changes in the illumination of the outer disk.

  13. Ringed Structures of the HD 163296 Protoplanetary Disk Revealed by ALMA

    Science.gov (United States)

    Isella, Andrea; Guidi, Greta; Testi, Leonardo; Liu, Shangfei; Li, Hui; Li, Shengtai; Weaver, Erik; Boehler, Yann; Carperter, John M.; De Gregorio-Monsalvo, Itziar; Manara, Carlo F.; Natta, Antonella; Pérez, Laura M.; Ricci, Luca; Sargent, Anneila; Tazzari, Marco; Turner, Neal

    2016-12-01

    We present Atacama Large Millimeter and Submillimeter Array observations of the protoplanetary disk around the Herbig Ae star HD 163296 that trace the spatial distribution of millimeter-sized particles and cold molecular gas on spatial scales as small as 25 astronomical units (A.U.). The image of the disk recorded in the 1.3 mm continuum emission reveals three dark concentric rings that indicate the presence of dust depleted gaps at about 60, 100, and 160 A.U. from the central star. The maps of the 12CO, 13CO, and C 18O J =2 -1 emission do not show such structures but reveal a change in the slope of the radial intensity profile across the positions of the dark rings in the continuum image. By comparing the observations with theoretical models for the disk emission, we find that the density of CO molecules is reduced inside the middle and outer dust gaps. However, in the inner ring there is no evidence of CO depletion. From the measurements of the dust and gas densities, we deduce that the gas-to-dust ratio varies across the disk and, in particular, it increases by at least a factor 5 within the inner dust gap compared to adjacent regions of the disk. The depletion of both dust and gas suggests that the middle and outer rings could be due to the gravitational torque exerted by two Saturn-mass planets orbiting at 100 and 160 A.U. from the star. On the other hand, the inner dust gap could result from dust accumulation at the edge of a magnetorotational instability dead zone, or from dust opacity variations at the edge of the CO frost line. Observations of the dust emission at higher angular resolution and of molecules that probe dense gas are required to establish more precisely the origins of the dark rings observed in the HD 163296 disk.

  14. Ringed Structures of the HD 163296 Protoplanetary Disk Revealed by ALMA.

    Science.gov (United States)

    Isella, Andrea; Guidi, Greta; Testi, Leonardo; Liu, Shangfei; Li, Hui; Li, Shengtai; Weaver, Erik; Boehler, Yann; Carperter, John M; De Gregorio-Monsalvo, Itziar; Manara, Carlo F; Natta, Antonella; Pérez, Laura M; Ricci, Luca; Sargent, Anneila; Tazzari, Marco; Turner, Neal

    2016-12-16

    We present Atacama Large Millimeter and Submillimeter Array observations of the protoplanetary disk around the Herbig Ae star HD 163296 that trace the spatial distribution of millimeter-sized particles and cold molecular gas on spatial scales as small as 25 astronomical units (A.U.). The image of the disk recorded in the 1.3 mm continuum emission reveals three dark concentric rings that indicate the presence of dust depleted gaps at about 60, 100, and 160 A.U. from the central star. The maps of the ^{12}CO, ^{13}CO, and C^{18}O J=2-1 emission do not show such structures but reveal a change in the slope of the radial intensity profile across the positions of the dark rings in the continuum image. By comparing the observations with theoretical models for the disk emission, we find that the density of CO molecules is reduced inside the middle and outer dust gaps. However, in the inner ring there is no evidence of CO depletion. From the measurements of the dust and gas densities, we deduce that the gas-to-dust ratio varies across the disk and, in particular, it increases by at least a factor 5 within the inner dust gap compared to adjacent regions of the disk. The depletion of both dust and gas suggests that the middle and outer rings could be due to the gravitational torque exerted by two Saturn-mass planets orbiting at 100 and 160 A.U. from the star. On the other hand, the inner dust gap could result from dust accumulation at the edge of a magnetorotational instability dead zone, or from dust opacity variations at the edge of the CO frost line. Observations of the dust emission at higher angular resolution and of molecules that probe dense gas are required to establish more precisely the origins of the dark rings observed in the HD 163296 disk.

  15. CHEMICAL IMAGING OF THE CO SNOW LINE IN THE HD 163296 DISK

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Chunhua; Öberg, Karin I.; Andrews, Sean M.; Wilner, David J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Bergin, Edwin A. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Hughes, A. Meredith [Van Vleck Observatory, Astronomy Department, Wesleyan University, 96 Foss Hill Drive, Middletown, CT 06459 (United States); Hogherheijde, Michiel [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); D’Alessio, Paola [Centro de Radioastronomi´a y Astrofísica, Universidad Nacional Autónoma de México, 58089 Morelia, Michoacán, México (Mexico)

    2015-11-10

    The condensation fronts (snow lines) of H{sub 2}O, CO, and other abundant volatiles in the midplane of a protoplanetary disk affect several aspects of planet formation. Locating the CO snow line, where the CO gas column density is expected to drop substantially, based solely on CO emission profiles, is challenging. This has prompted an exploration of chemical signatures of CO freeze-out. We present ALMA Cycle 1 observations of the N{sub 2}H{sup +} J = 3−2 and DCO{sup +} J = 4−3 emission lines toward the disk around the Herbig Ae star HD 163296 at ∼0.″5 (60 AU) resolution, and evaluate their utility as tracers of the CO snow line location. The N{sub 2}H{sup +} emission is distributed in a ring with an inner radius at 90 AU, corresponding to a midplane temperature of 25 K. This result is consistent with a new analysis of optically thin C{sup 18}O data, which implies a sharp drop in CO abundance at 90 AU. Thus N{sub 2}H{sup +} appears to be a robust tracer of the midplane CO snow line. The DCO{sup +} emission also has a ring morphology, but neither the inner nor the outer radius coincide with the CO snow line location of 90 AU, indicative of a complex relationship between DCO{sup +} emission and CO freeze-out in the disk midplane. Compared to TW Hya, CO freezes out at a higher temperature in the disk around HD 163296 (25 versus 17 K in the TW Hya disk), perhaps due to different ice compositions. This highlights the importance of actually measuring the CO snow line location, rather than assuming a constant CO freeze-out temperature for all disks.

  16. HST/ACS Coronagraphic Observations of the HD 163296 Circumstellar Disk: Evidence of Time-Variable Self-Shadowing?

    Science.gov (United States)

    Wisniewski, J.; Dowling, Lorraine; Clampin, Mark; Grady, C.; Ardila, D.; Golimowski, D.; Illingworth, G.; Krist, J.

    2007-01-01

    We present Hubble Space Telescope Advanced Camera for Surveys (HST/ACS) coronagraphic observations of the Herbig Ae star HD 163296. HD 163296's scattered light disk was resolved in the F606W and F814W filters in observations obtained In 2003 and in the F435W filter in observations obtained in 2004. Analysis of single-epoch data indicates that the disk (V-I) color is redder than the observed stellar (V-I) color. This spatially uniform red disk color might be indicative of either an evolution in the grain size distribution (i.e. grain growth) and/or composition. Both of these processes would be consistent with the observed flat geometry of the outer disk, as diagnosed by the observed r$(exp -3)$ power law behavior of its median azimuthally averaged disk surface brightness, which suggest that grain evolution is occurring. Comparison of ACS and STIS epoch scattered light data reveals differences in the observed disk surface brightnesses, of order 1 mag arcsec$(exp -2)$, in both V and white-light filter bandpasses. Along with the observed variability in the visibility and surface brightness of the ansa(e) in the disk, and spectropolarimetric variability of the system, these results suggest that the resolved scattered light disk is variable, a phenomenon not previously observed in any other Herbig protoplanetary system We speculate that the observed behavior might be attributable to the variable inflation of the scale height of the inner disk wall, which results in variable self-shadowing of the outer disk.

  17. Unveiling the gas and dust disk structure in HD 163296 using ALMA observations

    CERN Document Server

    de Gregorio-Monsalvo, I; Dent, W; Pinte, C; López, C; Klaassen, P; Hales, A; Cortés, P; Rawlings, M G; Tachihara, K; Testi, L; Takahashi, S; Chapillon, E; Mathews, G; Juhasz, A; Akiyama, E; Higuchi, A E; Saito, M; Nyman, L - Å; Phillips, N; Rodń, J; Corder, S; Van Kempen, T

    2013-01-01

    Aims: The aim of this work is to study the structure of the protoplanetary disk surrounding the Herbig Ae star HD 163296. Methods: We have used high-resolution and high-sensitivity ALMA observations of the CO(3-2) emission line and the continuum at 850 microns, as well as the 3- dimensional radiative transfer code MCFOST to model the data presented in this work. Results: The CO(3-2) emission unveils for the first time at sub-millimeter frequencies the vertical structure details of a gaseous disk in Keplerian rotation, showing the back- and the front-side of a flared disk. Continuum emission at 850 microns reveals a compact dust disk with a 240 AU outer radius and a surface brightness profile that shows a very steep decline at radius larger than 125 AU. The gaseous disk is more than two times larger than the dust disk, with a similar critical radius but with a shallower radial profile. Radiative transfer models of the continuum data confirms the need for a sharp outer edge to the dust disk. The models for the ...

  18. Resolving the CO Snow Line in the Disk around HD 163296

    CERN Document Server

    Qi, Chunhua; Oberg, Karin I; Wilner, David J; Hughes, A Meredith; Andrews, Sean M; Ayala, Sandra

    2011-01-01

    We report Submillimeter Array (SMA) observations of CO (J=2--1, 3--2 and 6--5) and its isotopologues (13CO J=2--1, C18O J=2--1 and C17O J=3--2) in the disk around the Herbig Ae star HD 163296 at ~2" (250 AU) resolution, and interpret these data in the framework of a model that constrains the radial and vertical location of the line emission regions. First, we develop a physically self-consistent accretion disk model with an exponentially tapered edge that matches the spectral energy distribution and spatially resolved millimeter dust continuum emission. Then, we refine the vertical structure of the model using wide range of excitation conditions sampled by the CO lines, in particular the rarely observed J=6--5 transition. By fitting 13CO data in this structure, we further constrain the vertical distribution of CO to lie between a lower boundary below which CO freezes out onto dust grains (T ~ 19 K) and an upper boundary above which CO can be photodissociated (the hydrogen column density from the disk surface ...

  19. Dust properties across the CO snowline in the HD 163296 disk from ALMA and VLA observations

    CERN Document Server

    Guidi, G; Testi, L; de Gregorio-Monsalvo, I; Chandler, C J; Pérez, L; Isella, A; Natta, A; Ortolani, S; Hennings, Th; Corder, S; Linz, H; Andrews, S; Wilner, D; Ricci, L; Carpenter, J; Sargent, A; Mundy, L; Storm, S; Calvet, N; Dullemond, C; Greaves, J; Lazio, J; Deller, A; Kwon, W

    2016-01-01

    To characterize the mechanisms of planet formation it is crucial to investigate the properties and evolution of protoplanetary disks around young stars, where the initial conditions for the growth of planets are set. Our goal is to study grain growth in the disk of the young, intermediate mass star HD163296 where dust processing has already been observed, and to look for evidence of growth by ice condensation across the CO snowline, already identified in this disk with ALMA. Under the hypothesis of optically thin emission we compare images at different wavelengths from ALMA and VLA to measure the opacity spectral index across the disk and thus the maximum grain size. We also use a Bayesian tool based on a two-layer disk model to fit the observations and constrain the dust surface density. The measurements of the opacity spectral index indicate the presence of large grains and pebbles ($\\geq$1 cm) in the inner regions of the disk (inside $\\sim$50 AU) and smaller grains, consistent with ISM sizes, in the outer ...

  20. WEAK TURBULENCE IN THE HD 163296 PROTOPLANETARY DISK REVEALED BY ALMA CO OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Flaherty, Kevin M.; Hughes, A. Meredith [Van Vleck Observatory, Astronomy Department, Wesleyan University, 96 Foss Hill Drive, Middletown, CT 06459 (United States); Rosenfeld, Katherine A.; Andrews, Sean M.; Wilner, David J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Chiang, Eugene; Kerzner, Skylar [Department of Earth and Planetary Science, 307 McCone Hall, University of California, Berkeley, CA 94720 (United States); Simon, Jacob B. [Department of Space Studies, Southwest Research Institute, Boulder, CO 80302 (United States)

    2015-11-10

    Turbulence can transport angular momentum in protoplanetary disks and influence the growth and evolution of planets. With spatially and spectrally resolved molecular emission line measurements provided by (sub)millimeter interferometric observations, it is possible to directly measure non-thermal motions in the disk gas that can be attributed to this turbulence. We report a new constraint on the turbulence in the disk around HD 163296, a nearby young A star, determined from Atacama Large Millimeter/submillimeter Array Science Verification observations of four CO emission lines (the CO(3-2), CO(2-1), {sup 13}CO(2-1), and C{sup 18}O(2-1) transitions). The different optical depths for these lines permit probes of non-thermal line-widths at a range of physical conditions (temperature and density) and depths into the disk interior. We derive stringent limits on the non-thermal motions in the upper layers of the outer disk such that any contribution to the line-widths from turbulence is <3% of the local sound speed. These limits are approximately an order of magnitude lower than theoretical predictions for full-blown magnetohydrodynamic turbulence driven by the magnetorotational instability, potentially suggesting that this mechanism is less efficient in the outer (R ≳ 30 AU) disk than has been previously considered.

  1. A Three-Dimensional View of Turbulence Amid Complex Structure in the HD 163296 Protoplanetary Disk

    Science.gov (United States)

    Flaherty, Kevin M.; Hughes, A. Meredith; Rose, Sanaea; Andrews, Sean M.; Wilner, David J.; Chiang, Eugene; Simon, Jacob B.

    2017-01-01

    Gas kinematics are an important part of planet formation, influencing processes ranging from the growth of sub-micron sized grains to the migration of gas giant planets. Dynamical behavior can be traced with both synoptic observations of the mid-infrared excess, sensitive to the inner disk, and spatially resolved radio observations of gas emission, sensitive to the outer disk. I report new constraints on the vertical structure of turbulence in the disk around HD 163296, based on ALMA observations of DCO+ and CO isotoplogues that are sensitive to different layers of the disk. These data place upper limits on the turbulence (ALMA constraints on turbulence amid differing ionization environments.

  2. GASPS observations of Herbig Ae/Be stars with PACS/Herschel. The atomic and molecular content of their protoplanetary discs

    CERN Document Server

    Meeus, G; Mendigutia, I; Kamp, I; Thi, W F

    2012-01-01

    We observed a sample of 20 representative Herbig Ae/Be stars and five A-type debris discs with PACS onboard of Herschel. The observations were done in spectroscopic mode, and cover far-IR lines of [OI], [CII], CO, CH+, H2O and OH. We have a [OI]63 micron detection rate of 100% for the Herbig Ae/Be and 0% for the debris discs. [OI]145 micron is only detected in 25%, CO J=18-17 in 45% (and less for higher J transitions) of the Herbig Ae/Be stars and for [CII] 157 micron, we often found spatially variable background contamination. We show the first detection of water in a Herbig Ae disc, HD 163296, which has a settled disc. Hydroxyl is detected as well in this disc. CH+, first seen in HD 100546, is now detected for the second time in a Herbig Ae star, HD 97048. We report fluxes for each line and use the observations as line diagnostics of the gas properties. Furthermore, we look for correlations between the strength of the emission lines and stellar or disc parameters, such as stellar luminosity, UV and X-ray fl...

  3. Stacking Spectra in Protoplanetary Disks: Detecting Intensity Profiles from Hidden Molecular Lines in HD 163296

    CERN Document Server

    Yen, Hsi-Wei; Liu, Hauyu Baobab; Puspitaningrum, Evaria; Hirano, Naomi; Lee, Chin-Fei; Takakuwa, Shigehisa

    2016-01-01

    We introduce a new stacking method in Keplerian disks that (1) enhances signal-to-noise ratios (S/N) of detected molecular lines and (2) that makes visible otherwise undetectable weak lines. Our technique takes advantage of the Keplerian rotational velocity pattern. It aligns spectra according to their different centroid velocities at their different positions in a disk and stacks them. After aligning, the signals are accumulated in a narrower velocity range as compared to the original line width without alignment. Moreover, originally correlated noise becomes de-correlated. Stacked and aligned spectra, thus, have a higher S/N. We apply our method to ALMA archival data of DCN (3-2), DCO+ (3-2), N2D+ (3-2), and H2CO (3_0,3-2_0,2), (3_2,2-2_2,1), and (3_2,1-2_2,0) in the protoplanetary disk around HD 163296. As a result, (1) the S/N of the originally detected DCN (3-2), DCO+ (3-2), and H2CO (3_0,3-2_0,2) and N2D+ (3-2) lines are boosted by a factor of >4-5 at their spectral peaks, implying one order of magnitud...

  4. ALMA imaging of the CO snowline of the HD 163296 disk with DCO+

    CERN Document Server

    Mathews, G S; Juhasz, A; Harsono, D; Chapillon, E; van Dishoeck, E F; Espada, D; de Gregorio-Monsalvo, I; Hales, A; Hogerheijde, M R; Mottram, J C; Rawlings, M G; Takahashi, S; Testi, L

    2013-01-01

    The high spatial and line sensitivity of ALMA opens the possibility of resolving emission from molecules in circumstellar disks. With an understanding of physical conditions under which molecules have high abundance, they can be used as direct tracers of distinct physical regions. In particular, DCO+ is expected to have an enhanced abundance within a few Kelvin of the CO freezeout temperature of 19 K, making it a useful probe of the cold disk midplane. We compare ALMA line observations of HD 163296 to a grid of models. We vary the upper- and lower-limit temperatures of the region in which DCO+ is present as well as the abundance of DCO+ in order to fit channel maps of the DCO+ J=5-4 line. To determine the abundance enhancement compared to the general interstellar medium, we carry out similar fitting to HCO+ J=4-3 and H13CO+ J=4-3 observations. ALMA images show centrally peaked extended emission from HCO+ and H13CO+. DCO+ emission lies in a resolved ring from ~110 to 160 AU. The outer radius approximately corr...

  5. Variability in the CO ro-vibrational lines from HD163296

    CERN Document Server

    Bertelsen, Rosina P Hein; van der Plas, G; Ancker, M E van den; Waters, L B F M; Thi, W -F; Woitke, P

    2016-01-01

    We present for the first time a direct comparison of multi-epoch (2001-2002 and 2012) CO ro-vibrational emission lines from HD163296. We find that both the line shapes and the FWHM (Full Width Half Maximum) differ between these two epochs. The FWHM of the median observed line profiles are 10-25 km/s larger in the earlier epoch, and confirmed double peaks are only present in high J lines from 2001-2002. The line wings of individual transitions are similar in the two epochs making an additional central component in the later epoch a likely explanation for the single peaks and the lower FWHM. Variations in NIR brightness have been reported and could be linked to the observed variations. Additionally, we use the thermo chemical disc code ProDiMo to compare for the first time the line shapes, peak separations, FWHM, and line fluxes, to those observed. The ProDiMo model reproduces the peak separations, and low and mid J line fluxes well. The FWHM however, are over predicted and high J line fluxes are under predicte...

  6. Stacking Spectra in Protoplanetary Disks: Detecting Intensity Profiles from Hidden Molecular Lines in HD 163296

    Science.gov (United States)

    Yen, Hsi-Wei; Koch, Patrick M.; Liu, Hauyu Baobab; Puspitaningrum, Evaria; Hirano, Naomi; Lee, Chin-Fei; Takakuwa, Shigehisa

    2016-12-01

    We introduce a new stacking method in Keplerian disks that (1) enhances signal-to-noise ratios (S/Ns) of detected molecular lines and (2) makes visible otherwise-undetectable weak lines. Our technique takes advantage of the Keplerian rotational velocity pattern. It aligns spectra according to their different centroid velocities at their different positions in a disk and stacks them. After aligning, the signals are accumulated in a narrower velocity range as compared to the original line width without alignment. Moreover, originally correlated noise becomes decorrelated. Stacked and aligned spectra thus have a higher S/N. We apply our method to Atacama Large Millimeter/Submillimeter Array (ALMA) archival data of DCN (3-2), DCO+ (3-2), N2D+ (3-2), and H2CO (3{}{0,3}-2{}{0,2}), (3{}{2,2}-2{}{2,1}), and (3{}{2,1}-2{}{2,0}) in the protoplanetary disk around HD 163296. As a result, (1) the S/Ns of the originally detected DCN (3-2), DCO+ (3-2), H2CO (3{}{0,3}-2{}{0,2}), and N2D+ (3-2) lines are boosted by a factor of ≳4-5 at their spectral peaks, implying one order of magnitude shorter integration times to reach the original S/N; and (2) the previously undetectable spectra of the H2CO (3{}{2,2}-2{}{2,1}) and (3{}{2,1}-2{}{2,0}) lines are materialized at more than 3σ. These dramatically enhanced S/Ns allow us to measure intensity distributions in all lines with high significance. The principle of our method can be applied not only to Keplerian disks but also to any systems with ordered kinematic patterns.

  7. Variability in the CO ro-vibrational lines from HD163296

    Science.gov (United States)

    Hein Bertelsen, Rosina P.; Kamp, I.; van der Plas, G.; van den Ancker, M. E.; Waters, L. B. F. M.; Thi, W.-F.; Woitke, P.

    2016-05-01

    We present for the first time a direct comparison of multi-epoch (2001-2002 and 2012) CO ro-vibrational emission lines from HD 163296. We find that both the line shapes and the FWHM (full width at half-maximum) differ between these two epochs. The FWHM of the median observed line profiles are 10-25 km s-1 larger in the earlier epoch, and confirmed double peaks are only present in high J lines from 2001 to 2002. The line wings of individual transitions are similar in the two epochs making an additional central component in the later epoch a likely explanation for the single peaks and the lower FWHM. Variations in near-infrared brightness have been reported and could be linked to the observed variations. Additionally, we use the thermo-chemical disc code PRODIMO to compare for the first time the line shapes, peak separations, FWHM, and line fluxes, to those observed. The PRODIMO model reproduces the peak separations, and low and mid J line fluxes well. The FWHM however, are overpredicted and high J line fluxes are underpredicted. We propose that a variable non-Keplerian component of the CO ro-vibrational emission, such as a disc wind or an episodic accretion funnel, is causing the difference between the two data sets collected at different epochs, and between model and observations. Additional CO ro-vibrational line detections (with cryogenic high-resolution infrared echelle spectrograph/Very Large Telescope (VLT) or Near InfraRed SPECtrometer/Keck) or [Ne II] line observations with VLT Imager and Spectrometer for mid Infrared/VLT could help to clarify the cause of the variability.

  8. Accretion Rates in Herbig Ae stars

    CERN Document Server

    López, R G; Testi, L; Habart, E

    2006-01-01

    Accretion rates from disks around pre-main sequence stars are of importance for our understanding of planetary formation and disk evolution. We provide in this paper estimates of the mass accretion rates in the disks around a large sample of Herbig Ae stars. We obtained medium resolution 2 micron spectra and used the results to compute values of Macc from the measured luminosity of the Br_gamma emission line, using a well established correlation between L(Br_gamma) and the accretion luminosity Lacc. We find that 80% of the stars, all of which have evidence of an associated circumstellar disk, are accreting matter, with rates 3x10^{-9} 10^{-7} Msun/yr. In most HAe stars the accretion rate is sufficiently low that the gas in the inner disk, inside the dust evaporation radius, is optically thin and does not prevent the formation of a puffed-up rim, where dust is directly exposed to the stellar radiation. When compared to the Macc values found for lower-mass stars in the star forming regions Taurus and Ophiuchus,...

  9. Magnetic fields of Herbig Ae/Be stars

    Directory of Open Access Journals (Sweden)

    Hubrig S.

    2014-01-01

    Full Text Available We report on the status of our spectropolarimetric studies of Herbig Ae/Be stars carried out during the last years. The magnetic field geometries of these stars, investigated with spectropolarimetric time series, can likely be described by centred dipoles with polar magnetic field strengths of several hundred Gauss. A number of Herbig Ae/Be stars with detected magnetic fields have recently been observed with X-shooter in the visible and the near-IR, as well as with the high-resolution near-IR spectrograph CRIRES. These observations are of great importance to understand the relation between the magnetic field topology and the physics of the accretion flow and the accretion disk gas emission.

  10. HARPS spectropolarimetry of Herbig Ae/Be stars

    CERN Document Server

    Hubrig, S; Schoeller, M; Curto, G Lo

    2013-01-01

    Our knowledge of the presence and the strength of magnetic fields in intermediate-mass pre-main-sequence stars remains very poor. We present new magnetic field measurements in six Herbig Ae/Be stars observed with HARPS in spectropolarimetric mode. We downloaded from the European Southern Observatory (ESO) archive the publically available HARPS spectra for six Herbig Ae/Be stars. Wavelength shifts between right- and left-hand side circularly polarised spectra were interpreted in terms of a longitudinal magnetic field , using the moment technique introduced by Mathys. The application of the moment technique to the HARPS spectra allowed us in addition to study the presence of the crossover effect and quadratic magnetic fields. Our search for longitudinal magnetic fields resulted in first detections of weak magnetic fields in the Herbig Ae/Be stars HD58647 and HD98922. Further, we confirm the previous tentative detection of a weak magnetic field in HD104237 by Donati et al. and confirm the previous detection of a...

  11. Magnetospheres and Disk Accretion in Herbig Ae/Be Stars

    CERN Document Server

    Muzerolle, J; Calvet, N; Hartmann, L

    2004-01-01

    We present evidence of magnetically-mediated disk accretion in Herbig Ae/Be stars. Magnetospheric accretion models of Balmer and sodium profiles calculated with appropriate stellar and rotational parameters are in qualitative agreement with the observed profiles of the Herbig Ae star UX Ori, and yield a mass accretion rate of ~ 10^{-8} Msun/yr. If more recent indications of an extremely large rotation rate for this object are correct, the magnetic field geometry must deviate from that of a standard dipole in order to produce line emission consistent with observed flux levels. Models of the associated accretion shock qualitatively explain the observed distribution of excess fluxes in the Balmer discontinuity for a large ensemble of Herbig Ae/Be stars, and imply typically small mass accretion rates, < 10^{-7} Msun/yr. In order for accretion to proceed onto the star, significant amounts of gas must exist inside the dust destruction radius, which is potentially problematic for recently advocated scenarios of "...

  12. The (BETA) Pictoris Phenomenon Among Herbig Ae/Be Stars

    Science.gov (United States)

    Grady, C. A.; Perez, M. R.; Talavera, A.; Bjorkman, K. S.; deWinter, D.; The, P.-S.; Molster, F. J.; vandenAncker, M. E.; Sitko, M. L.; Morrison, N. D.; Beaver, M. L.; McCollum, B.; Castelaz, M. W.

    1996-01-01

    We present a survey of high dispersion UV and optical spectra of Herbig Ae/Be (HAeBe) and related stars. We find accreting, circumstellar gas over the velocity range +100 to +400 km/s, and absorption profiles similar to those seen toward Beta Pic, in 36% of the 33 HAeBe stars with IUE data as well as in 3 non-emission B stars. We also find evidence of accretion in 7 HAeBe stars with optical data only. Line profile variability appears ubiquitous. As a group, the stars with accreting gas signatures have higher v sin i than the stars with outflowing material, and tend to exhibit large amplitude (greater than or equal to 1(sup m)) optical light variations. All of the program stars with polarimetric variations that are anti-correlated with the optical light, previously interpreted as the signature of a dust disk viewed close to equator-on, also show spectral signatures of accreting gas. These data imply that accretion activity in HAeBe stars is preferentially observed when the line of sight transits the circumstellar dust disk. Our data imply that the spectroscopic signatures of accreting circumstellar material seen in Beta Pic are not unique to that object, but instead are consistent with interpretation of Beta Pic as a comparatively young A star with its associated circumstellar disk.

  13. Infrared spectroscopy of the Herbig Ae-Be stars

    Science.gov (United States)

    Harvey, P. M.

    1984-01-01

    Infrared spectroscopy from 1.5-2.3 microns is presented for nine Ae and Be stars believed to be pre-main-sequence. Brackett-gamma emission is seen in most or all the spectra, and higher-order Brackett recombination lines are visible in a number of the spectra. The strengths of the emission lines are generally less than or equal to the expected fluxes from H II regions which have been postulated to explain Balmer and Paschen continuum excesses in these stars. The circumstellar H II regions may be optically thick in some of the Brackett lines. No other lines are visible in the spectra, e.g., He or H2. The infrared continua are generally smooth; they confirm the presence of excess emission over that expected from the stellar photospheres. If the excesses are produced by thermal emission from dust, the dust grains must exist up to temperatures of 1300 K-1500 K.

  14. ISO spectroscopy of disks around Herbig Ae/Be stars

    CERN Document Server

    Van den Ancker, M E

    2004-01-01

    We have investigated the infrared spectra of all 46 Herbig Ae/Be stars for which spectroscopic data is available in the ISO data archive. Our quantitative analysis of these spectra focusses on the emission bands linked to polycyclic aromatic hydrocarbons (PAHs), the amorphous 10 micron silicate band and the crystalline silicate band at 11.3 micron. We have detected PAH emission in 57% of the Herbig stars in our sample. Clear examples of differences in the PAH spectra are present within our sample, indicating differences in PAH size, chemistry and/or ionization. Amorphous silicate emission was detected in the spectra of 52% of the sample stars, amorphous silicate absorption in 13%. We have detected crystalline silicate emission in 11 stars (24% of our sample), of which four (9%) also display strong PAH emission. We have classified the sample sources according to the strength of their mid-IR energy distribution. The systems with stronger mid-infared (20-100 um) excesses relative to their near-infrared (1-5 um) ...

  15. Photometric variability of the Herbig Ae star HD 37806

    CERN Document Server

    Rucinski, S M; Hareter, M; Pojmanski, G; Kuschnig, R; Matthews, J M; Guenther, D B; Moffat, A F J; Sasselov, D; Weiss, W W

    2010-01-01

    The more massive counterparts of T Tauri stars, Herbig Ae/Be stars, are known to vary in a complex way with no variability mechanism clearly identified. We attempt to characterize the optical variability of HD~37806 (MWC 120) on time scales ranging between minutes and several years. A continuous, one-minute resolution, 21 day-long sequence of MOST (Microvariability & Oscillations of STars) satellite observations has been analyzed using wavelet, scalegram and dispersion analysis tools. The MOST data have been augmented by sparse observations over 9 seasons from ASAS (All Sky Automated Survey), by previously non-analyzed ESO (European Southern Observatory) data partly covering 3 seasons and by archival measurements dating back half a century ago. Mutually superimposed flares or accretion instabilities grow in size from about 0.0003 of the mean flux on a time scale of minutes to a peak-to-peak range of <~0.05 on a time scale of a few years. The resulting variability has properties of stochastic "red" nois...

  16. The Disk Atmospheres of Three Herbig Ae/Be Stars

    CERN Document Server

    Harker, D E; Wooden, D H; Temi, P; Harker, David E.; Woodward, Charles E.; Wooden, Diane H.; Temi, Pasquale

    2004-01-01

    We present infrared (IR) spectrophotometry ($R \\simeq 180$) of three Herbig Ae/Be stars surrounded by possible protoplanetary disks: HD 150193, HD100546 and HD 179218. We construct a mid-IR spectral energy distributions (SED) for each object by using $7.6 - 13.2$ \\micron HIFOGS spectra, 2.4 -- 45 \\micron\\ spectrophotometry from the {\\it ISO} SWS, the 12, 25, 60, and 100 \\micron\\ photometric points from IRAS, and for HD 179218, photometric bolometric data points from the Mt. Lemmon Observing Facility. The SEDs are modeled by using an expanded version of the \\citet{chigol97} two-layer, radiative and hydrostatic equilibrium, passive disk. This expanded version includes the emission from Mg-pure crystalline olivine (forsterite) grains in the disk surface layer. HD 150193 contains no crystals while HD 100546 and HD 179218 respectively show evidence of having crystalline silicates in the surface layers of their disks. We find that the inner region of HD100546 has a 37% higher crystalline-to-amorphous silicate ratio...

  17. The onset of cluster formation around Herbig Ae/Be stars

    CERN Document Server

    Testi, L; Natta, A

    1999-01-01

    The large body of near infrared observations presented in Testi et al. (1997; 1998) are analysed with the aim of characterizing the young stellar clusters surrounding Herbig Ae/Be stars. The results confirm the tendency of early Be stars to be surrounded by dense clusters of lower mass "companions", while Ae stars are never found to be associated with conspicuous groups. The transition between the different environments appears to occur smoothly from Ae to Be stars without a sharp threshold. No correlation of the richness of the stellar groups detected is found with the galactic position or the age of the central Herbig Ae/Be star. The stellar volume densities estimated for the groups surrounding pre-main-sequence stars of intermediate mass show the transition from the low density aggregates of T Tauri stars and the dense clusters around massive stars. Only the most massive stars (10-20Msun) are found to be associated with dense (10^3 pc^-3) stellar clusters. This is exactly the mass regime at which the conve...

  18. X-ray Study of the Intermediate-Mass Young Stars Herbig Ae/Be Stars

    CERN Document Server

    Hamaguchi, K; Koyama, K; Hamaguchi, Kenji; Yamauchi, Shigeo; Koyama, Katsuji

    2004-01-01

    We present the ASCA results of intermediate-mass pre-main-sequence stars (PMSs), or Herbig Ae/Be stars (HAeBes). Among the 35 ASCA pointed-sources, we detect 11 plausible X-ray counterparts. X-ray luminosities of the detected sources in the 0.5-10 keV band are in the range of log LX ~30-32 ergs s-1, which is systematically higher than those of low-mass PMSs. This fact suggests that the contribution of a possible low-mass companion is not large. Most of the bright sources show significant time variation, particularly, two HAeBes - MWC 297 and TY CrA - exhibit flare-like events with long decay timescales (e-folding time ~ 10-60 ksec). These flare shapes are similar to those of low-mass PMSs. The X-ray spectra are successfully reproduced by an absorbed one or two-temperature thin-thermal plasma model. The temperatures are in the range of kT ~1-5 keV, which are significantly higher than those of main-sequence OB stars (kT < 1 keV). These X-ray properties are not explained by wind driven shocks, but are more li...

  19. Chemical spots on the surface of the strongly magnetic Herbig Ae star HD 101412

    DEFF Research Database (Denmark)

    Järvinen, S. P.; Hubrig, S.; Schöller, M.;

    2016-01-01

    Due to the knowledge of the rotation period and the presence of a rather strong surface magnetic field, the sharp-lined young Herbig Ae star HD 101412 with a rotation period of 42 d has become one of the most well-studied targets among the Herbig Ae stars. High-resolution HARPS polarimetric spectra...... of HD 101412 were recently obtained on seven different epochs. Our study of the spectral variability over the part of the rotation cycle covered by HARPS observations reveals that the line profiles of the elements Mg, Si, Ca, Ti, Cr, Mn, Fe, and Sr are clearly variable while He exhibits variability...

  20. Spectro-astrometric Study of HI emission lines from Herbig Ae/Be Stars

    Science.gov (United States)

    Cade Adams, Steven; Brittain, Sean D.; Dougados, Catherine; Benisty, Myriam; Podio, Linda; Whelan, Emma

    2015-01-01

    We present a spectro-astrometric study of the Pa β and Br γ lines from six Herbig Ae/Be stars using NIFS on Gemini North. The goal of this study is to determine the origin of the HI emission lines. By combining the high angular resolution ( 0.1") and intermediate spectral resolution (R~5000) of GEMINI/NIFS we measured the spectro-astrometric signal of the Pa β and Br γ emission lines at the 0.1 mas level. The HAe stars showed no significant spectro-astrometric signal, while the HBe stars did show significant detections. We compare our results to models and discuss the implications for understanding the origin of the HI lines in Herbig Ae/Be stars and their utility for measuring the accretion rate. We also discuss various artifacts in the data and prospects for more sensitive measurements in the future.

  1. Resolved Inner Disks around Herbig Ae/Be Stars

    CERN Document Server

    Eisner, J A; Hillenbrand, L A; Akeson, R L; Sargent, A I

    2004-01-01

    We have observed 14 Herbig Ae/Be sources with the long-baseline near-IR Palomar Testbed Interferometer, All except two sources are resolved at 2.2 um, with angular sizes generally <5 mas. We determine the size scales and orientations of the 2.2 um emission using various models: uniform disks, Gaussians, uniform rings, flat accretion disks with inner holes, and flared disks with puffed-up inner rims; 7 objects display significantly inclined morphologies, generally compatible with the outer disk geometries inferred from millimeter interferometric observations, implying that HAEBE disks are not significantly warped. Using the derived inner disk sizes and inclinations, we compute the spectral energy distributions for two simple physical disk models, and compare these with observed SEDs compiled from the literature and new near-IR photometry. While geometrically flat accretion disk models are consistent with the data for the earliest spectral types in our sample (MWC 297, V1685 Cyg, and MWC 1080), the later-typ...

  2. Studies of a possible new Herbig Ae/Be star in the open cluster NGC 7380

    Institute of Scientific and Technical Information of China (English)

    Blesson Mathew; D. P. K. Banerjee; N. M. Ashok; Annapurni Subramaniam; Bhaskaran Bhavya; Vishal Joshi

    2012-01-01

    We present a study of the star 2MASS J22472238+5801214 with the aim of identifying its true nature which has hitherto been uncertain.This object,which is a member of the young cluster NGC 7380,has been variously proposed to be a Be star,a D-type symbiotic and a Herbig Ae/Be star in separate studies.Here we present optical spectroscopy,near-IR photometry and narrow band Hα imaging of the nebulosity in its environment.Analysis of all these results,including the spectral energy distribution constructed from available data,strongly indicate the source to be a Herbig Ae/Be star.The star is found to be accompanied by a nebulosity with an interesting structure.A bow-shock shaped structure,similar to a cometary nebula,is seen very close to the star with its apex oriented towards the photoionizing source of this region (i.e.the star DH Cep).An interesting spectroscopic finding,from the forbidden [SⅡ] 6716,6731 (A) and [OI] 6300 (A) lines,is the detection of a blue-shifted high velocity outflow (200 ±50 km s- 1) from the star.

  3. How non-magnetic are "non-magnetic" Herbig Ae/Be stars?

    CERN Document Server

    Wade, G A; Catala, C; Bagnulo, S; Landstreet, J D; Flood, J; Böhm, T; Bouret, J -C; Donati, J -F; Folsom, C P; Grunhut, J; Silvester, J

    2007-01-01

    Our recent discovery of magnetic fields in a small number of Herbig Ae/Be stars has required that we survey a much larger sample of stars. From our FORS1 and ESPaDOnS surveys, we have acquired about 125 observations of some 70 stars in which no magnetic fields are detected. Using a Monte Carlo approach, we have performed statistical comparisons of the observed longitudinal fields and LSD Stokes V profiles of these apparently non-magnetic stars with a variety of field models. This has allowed us to derive general upper limits on the presence of dipolar fields in the sample, and to place realistic upper limits on undetected dipole fields which may be present in individual stars. This paper briefly reports the results of the statistical modeling, as well as field upper limits for individual stars of particular interest.

  4. The prevalence of weak magnetic fields in Herbig Ae stars: The case of PDS2

    CERN Document Server

    Hubrig, S; Schöller, M; Ilyin, I

    2015-01-01

    Models of magnetically driven accretion and outflows reproduce many observational properties of T Tauri stars, but the picture is much less clear for the Herbig Ae/Be stars, due to the poor knowledge of their magnetic field strength and topology. The Herbig Ae star PDS2 was previously included in two magnetic studies based on low-resolution spectropolarimetric observations. Only in one of these studies the presence of a weak mean longitudinal magnetic field was reported. In the present study, for the first time, high-resolution HARPS spectropolarimetric observations of PDS2 are used to investigate the presence of a magnetic field. A firm detection of a weak longitudinal magnetic field is achieved using the multi-line singular value decomposition method for Stokes profile reconstruction (=33+-5G). To gain better knowledge of typical magnetic field strengths in late Herbig Be and Herbig Ae stars, we compiled previous magnetic field measurements, revealing that only very few stars have fields stronger than 200G,...

  5. X-shooting Herbig Ae/Be stars: Accretion probed by near-infrared He I emission

    NARCIS (Netherlands)

    Oudmaijer, R.D.; Van Den Ancker, M. E.; Baines, D.; Caselli, P.; Drew, J.E.; Hoare, M.G.; Lumsden, S.L.; Montesinos, B.; Sim, S.; Vink, J.S.; Wheelwright, H.E.; de Wit, W.J.M.

    2011-01-01

    The Herbig Ae/Be stars are intermediate mass pre-main sequence stars that bridge the gap between the low mass T Tauri stars and the Massive Young Stellar Objects. In this mass range, the acting star forming mechanism switches from magnetically controlled accretion to an as yet unknown mechanism, but

  6. Einstein X-ray observations of Herbig Ae/Be stars

    Science.gov (United States)

    Damiani, F.; Micela, G.; Sciortino, S.; Harnden, F. R., Jr.

    1994-01-01

    We have investigated the X-ray emission from Herbig Ae/Be stars, using the full set of Einstein Imaging Proportional Counter (IPC) observations. Of a total of 31 observed Herbig stars, 11 are confidently identified with X-ray sources, with four additonal dubious identifications. We have used maximum likelihood luminosity functions to study the distribution of X-ray luminosity, and we find that Be stars are significantly brighter in X-rays than Ae stars and that their X-ray luminosity is independent of projected rotational velocity v sin i. The X-ray emission is instead correlated with stellar bolometric luminosity and with effective temperature, and also with the kinetic luminosity of the stellar wind. These results seem to exclude a solar-like origin for the X-ray emission, a possibility suggested by the most recent models of Herbig stars' structure, and suggest an analogy with the X-ray emission of O (and early B) stars. We also observe correlations between X-ray luminosity and the emission at 2.2 microns (K band) and 25 microns, which strengthen the case for X-ray emission of Herbig stars originating in their circumstellar envelopes.

  7. Studies of a possible new Herbig Ae/Be star in the open cluster NGC 7380

    CERN Document Server

    Mathew, Blesson; Ashok, N M; Subramaniam, Annapurni; Bhavya, B; Joshi, Vishal

    2012-01-01

    We present a study of the star 2MASS J22472238+5801214 with the aim of identifying its true nature which has hitherto been uncertain. This object, which is a member of the young cluster NGC 7380, has been variously proposed to be a Be star, a D-type symbiotic and a Herbig Ae/Be star in separate studies. Here we present optical spectroscopy, near-IR photometry and narrow band H-alpha imaging of the nebulosity in its environment. Analysis of all these results, including the spectral energy distribution constructed from available data, strongly indicate the source to be a Herbig Ae/Be star. The star is found to be accompanied by a nebulosity with an interesting structure. A bow shock shaped structure, similar to a cometary nebula, is seen very close to the star with its apex oriented towards the photoionizing source of this region (i.e. the star DH Cep). An interesting spectroscopic finding, from the forbidden [SII] 6716, 6731 \\AA and [OI] 6300 \\AA lines, is the detection of a blue-shifted high velocity outflow ...

  8. Evolution of the dust/gas environment around Herbig Ae/Be stars

    CERN Document Server

    Liu, Tie; Wu, Yuefang; Qin, Sheng-Li; Miller, Martin

    2011-01-01

    With the KOSMA 3-m telescope, 54 Herbig Ae/Be stars were surveyed in CO and $^{13}$CO emission lines. The properties of the stars and their circumstellar environments are studied by fitting the SEDs. The mean line width of $^{13}$CO (2-1) lines of this sample is 1.87 km s$^{-1}$. The average column density of H$_{2}$ is found to be $4.9\\times10^{21}$ cm$^{-2}$ for the stars younger than $10^{6}$ yr, while drops to $2.5\\times10^{21}$ cm$^{-2}$ for those older than $10^{6}$ yr. No significant difference is found among the SEDs of Herbig Ae stars and Herbig Be stars at the same age. The infrared excess decreases with age. The envelope masses and the envelope accretion rates decease with age after $10^{5}$ yr. The average disk mass of the sample is $3.3\\times10^{-2} M_{\\sun}$. The disk accretion rate decreases more slowly than the envelope accretion rate. A strong correlation between the CO line intensity and the envelope mass is found.

  9. Comparison between accretion-related properties of Herbig Ae/Be and T Tauri stars

    CERN Document Server

    Mendigutía, I

    2013-01-01

    This paper summarizes several results concerning the comparison between accretion-related properties of cool (T Tauri; T < 7000 K, M < 1 Msun and hot (Herbig Ae/Be; 7000 < T(K) < 13000; 1 < M(Msun) < 6) pre-main sequence (PMS) stars. This comparison gives insight into the analogies/differences in the physics of the star-disk interaction and in the physical mechanisms driving disk dissipation. Several optical and near-IR line luminosities used for low-mass objects are also valid to estimate typical accretion rates for intermediate-mass stars under similar empirical expressions. In contrast, the Halpha width at 10% of peak intensity is used as an accretion tracer for T Tauris, but is not reliable to estimate accretion rates for Herbig Ae/Bes. This can be explained as a consequence of the different stellar rotation rates that characterize both types of stars. In addition, there are similar trends when the accretion rate is related to the near-IR colours and disk masses, suggesting that viscous ...

  10. NuSTAR and swift observations of the fast rotating magnetized white dwarf AE Aquarii

    DEFF Research Database (Denmark)

    Kitaguchi, Takao; An, Hongjun; Beloborodov, Andrei M.;

    2014-01-01

    AE Aquarii is a cataclysmic variable with the fastest known rotating magnetized white dwarf (P-spin = 33.08 s). Compared to many intermediate polars, AE Aquarii shows a soft X-ray spectrum with a very low luminosity (L-X similar to 10(31) erg s(-1)). We have analyzed overlapping observations...... of this system with the NuSTAR and the Swift X-ray observatories in 2012 September. We find the 0.5-30 keV spectra to be well fitted by either an optically thin thermal plasma model with three temperatures of 0.75(-0.45)(+0.18), 2.29(-0.82)(+0.96), and 9.33(-2.18)(+6.07) keV, or an optically thin thermal plasma...

  11. Chemical spots on the surface of the strongly magnetic Herbig Ae star HD 101412

    CERN Document Server

    Järvinen, S P; Schöller, M; Ilyin, I; Carroll, T A; Korhonen, H

    2016-01-01

    Due to the knowledge of the rotation period and the presence of a rather strong surface magnetic field, the sharp-lined young Herbig Ae star HD 101412 with a rotation period of 42 d has become one of the most well-studied targets among the Herbig Ae stars. High-resolution HARPS polarimetric spectra of HD 101412 were recently obtained on seven different epochs. Our study of the spectral variability over the part of the rotation cycle covered by HARPS observations reveals that the line profiles of the elements Mg, Si, Ca, Ti, Cr, Mn, Fe, and Sr are clearly variable while He exhibits variability that is opposite to the behaviour of the other elements studied. Since classical Ap stars usually show a relationship between the magnetic field geometry and the distribution of element spots, we used in our magnetic field measurements different line samples belonging to the three elements with the most numerous spectral lines, Ti, Cr, and Fe. Over the time interval covered by the available spectra, the longitudinal magn...

  12. The Mid-Infrared Polarization of the Herbig Ae Star WL 16: An Interstellar Origin?

    CERN Document Server

    Zhang, Han; Pantin, Eric; Li, Dan; Wright, Christopher M; Mariñas, Naibí; Barnes, Peter; Li, Aigen; Packham, Christopher

    2016-01-01

    We present high-resolution (0".4) mid-infrared (mid-IR) polarimetric images and spectra of WL 16, a Herbig Ae star at a distance of 125 pc. WL 16 is surrounded by a protoplanetary disk of $\\sim$ 900 AU in diameter, making it one of the most extended Herbig Ae/Be disks as seen in the mid-IR. The star is behind, or embedded in, the $\\rho$ Ophiuchus molecular cloud, and obscured by 28 magnitudes of extinction at optical wavelengths by the foreground cloud. Mid-IR polarization of WL 16, mainly arises from aligned elongated dust grains present along the line of sight, suggesting a uniform morphology of polarization vectors with an orientation of 33\\degr (East from North) and a polarization fraction of $\\sim$ 2.0\\%. This orientation is consistent with previous polarimetric surveys in the optical and near-IR bands to probe large-scale magnetic fields in the Ophiuchus star formation region, indicating that the observed mid-IR polarization toward WL 16 is produced by the dichroic absorption of magnetically aligned for...

  13. The circumstellar disc around the Herbig AeBe star HD169142

    CERN Document Server

    Dent, W R F; Osorio, M; Calvet, N; Anglada, G

    2006-01-01

    We present 7 mm and 3.5 cm wavelength continuum observations toward the Herbig AeBe star HD169142 performed with the Very Large Array (VLA) with an angular resolution of ~1". We find that this object exhibits strong (~4.4 mJy), unresolved (~1") 7 mm continuum emission, being one of the brightest isolated Herbig AeBe stars ever detected with the VLA at this wavelength. No emission is detected at 3.5 cm continuum, with a 3 sigma upper limit of ~0.08 mJy. From these values, we obtain a spectral index of ~2.5 in the 3.5 cm to 7 mm wavelength range, indicating that the observed flux density at 7mm is most likely dominated by thermal dust emission coming from a circumstellar disc. We use available photometric data from the literature to model the spectral energy distribution (SED) of this object from radio to near-ultraviolet frequencies. The observed SED can be understood in terms of an irradiated accretion disc with low mass accretion rate, 10^{-8} solar masses per year, surrounding a star with an age of ~10 Myr....

  14. MOST observations of the Herbig Ae {\\delta}-Scuti star HD 34282

    CERN Document Server

    Casey, M P; Guenther, D B; Weiss, W W; Amado, P J; Díaz-Fraile, D; Rodriguez, E; Kuschnig, R; Matthews, J M; Moffat, A F J; Rowe, J F; Rucinski, S M; Sasselov, D

    2012-01-01

    MOST observations and model analysis of the Herbig Ae star HD 34282 (V1366 Ori) reveal {\\delta}-Scuti pulsations. 22 frequencies are observed, 10 of which confirm those previously identified by Amado et al. (2006), and 12 of which are newly discovered in this work. We show that the weighted-average frequency in each group fits the radial p-mode frequencies of viable models. We argue that the observed pulsation spectrum extends just to the edge to the acoustic cut-off frequency and show that this also is consistent with our best-fitting models.

  15. PAH Emission from Disks around Intermediate-Mass Stars: The Peculiar Aroma of Hydrocarbons Orbiting Herbig Ae/Be Stars

    Science.gov (United States)

    Keller, L. D.; Sloan, G. C.

    2009-12-01

    Over half of the intermediate-mass young stellar objects in the Galaxy (e.g. Herbig Ae/Be stars or HAeBe) have high-contrast emission in the mid-infrared spectral features of polycyclic aromatic hydrocarbons (PAHs) above the continuum produced by thermal emission from dust in the circumstellar disks. We have examined the PAH emission in detail for 30 HAeBe stars observed with the Spitzer IRS. We have identified some trends that, should they survive in a larger sample of HAeBe stars, will allow us to infer large-scale disk geometry (both inner and outer) and the degree of photo-processing of organic molecular material in HAeBe disks: HAeBe stars apparently have distinctive PAH spectra among the many other astronomical environments that are characterized by strong PAH emission; strong PAH emission is not necessarily an indicator of a particular disk geometry; PAH spectra of HAeBe stars change systematically with stellar effective temperature; PAH in HAeBe disks are ionized. As part of a Spitzer archival project we are applying our spectral analysis methods to an even larger sample of HAeBe stars observed with the IRS and currently available in the Spitzer archive. Here we report preliminary results as we begin the larger study.

  16. Discovery of non-radial pulsations in the spectroscopic binary Herbig Ae star RS Cha

    CERN Document Server

    Böhm, T; Catala, C; Alecian, E; Pollard, K; Wright, D

    2008-01-01

    In this article we present a first discovery of non radial pulsations in both components of the Herbig Ae spectroscopic binary star RS Cha. The binary was monitored in quasi-continuous observations during 14 observing nights (Jan 2006) at the 1m Mt John (New Zealand) telescope with the Hercules high-resolution echelle spectrograph. The cumulated exposure time on the star was 44 hrs, corresponding to 255 individual high-resolution echelle spectra with $R = 45000$. Least square deconvolved spectra (LSD) were obtained for each spectrum representing the effective photospheric absorption profile modified by pulsations. Difference spectra were calculated by subtracting rotationally broadened artificial profiles; these residual spectra were analysed and non-radial pulsations were detected. A subsequent analysis with two complementary methods, namely Fourier Parameter Fit (FPF) and Fourier 2D (F2D) has been performed and first constraints on the pulsation modes have been derived. In fact, both components of the spect...

  17. Disk wind and magnetospheric accretion in emission from the Herbig Ae star MWC 480

    Science.gov (United States)

    Tambovtseva, L. V.; Grinin, V. P.; Potravnov, I. S.; Mkrtichian, D. E.

    2016-09-01

    The young Herbig Ae star MWC 480 (HD 31648) is one of the comprehensively spectroscopically studied stars in the ultraviolet, optical, and infrared spectral ranges. Using non-LTE modeling of its hydrogen spectrum, we have calculated the contribution to the hydrogen emission from such important regions of the circumstellar environment as the disk wind and the magnetosphere. We have used our own observations of the stellar spectrum performed with the 2.4-m telescope at the Thai National Observatory to quantitatively check our theoretical calculations. In addition, all of the visible and infrared spectra available in the literature have been used for a qualitative comparison. The modeling results have revealed a significant role of the magneto-centrifugal disk wind in the formation of atomic hydrogen emission. The cause of the emission line variability in the spectrum ofMWC 480 is discussed.

  18. The magnetic field of the pre-main sequence Herbig Ae star HD 190073

    Science.gov (United States)

    Catala, C.; Alecian, E.; Donati, J.-F.; Wade, G. A.; Landstreet, J. D.; Böhm, T.; Bouret, J.-C.; Bagnulo, S.; Folsom, C.; Silvester, J.

    2007-01-01

    Context: The general context of this paper is the study of magnetic fields in the pre-main sequence intermediate mass Herbig Ae/Be stars. Magnetic fields are likely to play an important role in pre-main sequence evolution at these masses, in particular in controlling the gains and losses of stellar angular momentum. Aims: The particular aim of this paper is to announce the detection of a structured magnetic field in the Herbig Ae star HD 190073, and to discuss various scenarii for the geometry of the star, its environment and its magnetic field. Methods: We have used the ESPaDOnS spectropolarimeter at CFHT in 2005 and 2006 to obtain high-resolution, high signal-to-noise circular polarization spectra which demonstrate unambiguously the presence of a magnetic field in the photosphere of this star. Results: Nine circular polarization spectra were obtained, each one showing a clear Zeeman signature. This signature is suggestive of a magnetic field structured on large scales. The signature, which corresponds to a longitudinal magnetic field of 74± 10 G, does not vary detectably on a one-year timeframe, indicating either an azimuthally symmetric field, a zero inclination angle between the rotation axis and the line of sight, or a very long rotation period. The optical spectrum of HD 190073 exhibits a large number of emission lines. We discuss the formation of these emission lines in the framework of a model involving a turbulent heated region at the base of the stellar wind, possibly powered by magnetic accretion. Conclusions: .This magnetic detection contributes an important new observational discovery which will aid our understanding of stellar magnetism at intermediate masses. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

  19. The mid-infrared polarization of the Herbig Ae star WL 16: an interstellar origin?

    Science.gov (United States)

    Zhang, Han; Telesco, Charles M.; Pantin, Eric; Li, Dan; Wright, Christopher M.; Mariñas, Naibí; Barnes, Peter; Li, Aigen; Packham, Christopher

    2017-03-01

    We present high-resolution (0.4 arcsec) mid-infrared (mid-IR) polarimetric images and spectra of WL 16, a Herbig Ae star at a distance of 125 pc. WL 16 is surrounded by a protoplanetary disc of ∼ 900 au in diameter, making it one of the most extended Herbig Ae/Be discs as seen in the mid-IR. The star is behind, or embedded in, the ρ Ophiuchus molecular cloud, and obscured by 28 mag of extinction at optical wavelengths by the foreground cloud. Mid-IR polarization of WL 16 mainly arises from aligned elongated dust grains present along the line of sight, suggesting a uniform morphology of polarization vectors with an orientation of 33°(east from north) and a polarization fraction of ∼ 2.0 per cent. This orientation is consistent with previous polarimetric surveys in the optical and near-IR bands to probe large-scale magnetic fields in the Ophiuchus star formation region, indicating that the observed mid-IR polarization towards WL 16 is produced by the dichroic absorption of magnetically aligned foreground dust grains by a uniform magnetic field. Using polarizations of WL 16 and Elias 29, a nearby polarization standard star, we constrain the polarization efficiency, p10.3/A10.3, for the dust grains in the ρ Ophiuchus molecular cloud to be ≃1.0 per cent mag-1. WL 16 has polycyclic aromatic hydrocarbon (PAH) emission features detected at 8.6, 11.2, 12.0, and 12.7 μm by our spectroscopic data, and we find an anticorrelation between the PAH surface brightness and the PAH ionization fraction between the north-west and south-west sides of the disc.

  20. Dust evolution in protoplanetary disks around Herbig Ae/Be stars - The Spitzer view

    CERN Document Server

    Juhasz, A; Henning, Th; Acke, B; Ancker, M E van den; Meeus, G; Dominik, C; Min, M; Tielens, A G G M; Waters, L B F M

    2010-01-01

    In this paper we present mid-infrared spectra of a comprehensive set of Herbig Ae/Be stars observed with the Spitzer Space Telescope. The signal-to-noise ratio of these spectra is very high, ranging between about a hundred and several hundreds. During the analysis of these data we tested the validity of standard protoplanetary dust models and studied grain growth and crystal formation. On the basis of the analyzed spectra, the major constituents of protoplanetary dust around Herbig Ae/Be stars are amorphous silicates with olivine and pyroxene stoichiometry, crystalline forsterite and enstatite and silica. No other solid state features, indicating other abundant dust species, are present in the Spitzer spectra. Deviations of the synthetic spectra from the observations are most likely related to grain shape effects and uncertainties in the iron content of the dust grains. Our analysis revealed that larger grains are more abundant in the disk atmosphere of flatter disks than in that of flared disks, indicating t...

  1. A high-resolution spectropolarimetric survey of Herbig Ae/Be stars - I. Observations and measurements

    CERN Document Server

    Alecian, E; Catala, C; Grunhut, J H; Landstreet, J D; Bagnulo, S; Böhm, T; Folsom, C P; Marsden, S; Waite, I

    2012-01-01

    This is the first in a series of papers in which we describe and report the analysis of a large survey of Herbig Ae/Be stars in circular spectropolarimetry. Using the ESPaDOnS and Narval high-resolution spectropolarimeters at the Canada-France-Hawaii and Bernard Lyot Telescopes, respectively, we have acquired 132 circularly-polarised spectra of 70 Herbig Ae/Be stars and Herbig candidates. The large majority of these spectra are characterised by a resolving power of about 65,000, and a spectral coverage from about 3700 ang to 1 micron. The peak SNR per CCD pixel ranges from below 100 (for the faintest targets) to over 1000 (for the brightest). The observations were acquired with the primary aim of searching for magnetic fields in these objects. However, our spectra are suitable for a variety of other important measurements, including rotational properties, variability, binarity, chemical abundances, circumstellar environment conditions and structure, etc. In this first paper, we describe the sample selection, ...

  2. A parameter study of self-consistent disk models around Herbig AeBe stars

    CERN Document Server

    Meijer, J; De Koter, A; Dullemond, C P; Van Boekel, R; Waters, L B F M

    2008-01-01

    We present a parameter study of self-consistent models of protoplanetary disks around Herbig AeBe stars. We use the code developed by Dullemond and Dominik, which solves the 2D radiative transfer problem including an iteration for the vertical hydrostatic structure of the disk. This grid of models will be used for several studies on disk emission and mineralogy in followup papers. In this paper we take a first look on the new models, compare them with previous modeling attempts and focus on the effects of various parameters on the overall structure of the SED that leads to the classification of Herbig AeBe stars into two groups, with a flaring (group I) or self-shadowed (group II) SED. We find that the parameter of overriding importance to the SED is the total mass in grains smaller than 25um, confirming the earlier results by Dullemond and Dominik. All other parameters studied have only minor influences, and will alter the SED type only in borderline cases. We find that there is no natural dichotomy between ...

  3. Near-Infrared Interferometric Measurements of Herbig Ae/Be Stars

    CERN Document Server

    Eisner, J A; Akeson, R L; Hillenbrand, L A; Sargent, A I

    2003-01-01

    We have observed the Herbig Ae/Be sources AB Aur, VV Ser, V1685 Cyg (BD+40 4124), AS 442, and MWC 1080 with the Palomar Testbed Interferometer, obtaining the longest baseline near-IR interferometric observations of this class of objects. All of the sources are resolved at 2.2 microns with angular size scales generally <5 mas, consistent with the only previous near-IR interferometric measurements of Herbig Ae/Be stars by Millan-Gabet and collaborators. We determine the angular size scales and orientations predicted by uniform disk, Gaussian, ring, and accretion disk models. Although it is difficult to distinguish different radial distributions, we are able to place firm constraints on the inclinations of these models, and our measurements are the first that show evidence for significantly inclined morphologies. In addition, the derived angular sizes for the early type Herbig Be stars in our sample, V1685 Cyg and MWC 1080, agree reasonably well with those predicted by the face-on accretion disk models used b...

  4. Mid-infrared spectra of PAH emission in Herbig AeBe stars

    CERN Document Server

    Sloan, G C; Forrest, W J; Leibensperger, E; Sargent, B; Li, A; Najita, J; Watson, D M; Brandl, B R; Chen, C H; Green, J D; Markwick-Kemper, F; Herter, T L; D'Alessio, P; Morris, P W; Barry, J; Hall, P; Myers, P C; Houck, J R

    2005-01-01

    We present spectra of four Herbig AeBe stars obtained with the Infrared Spectrograph (IRS). on the Spitzer Space Telescope. All four of the sources show strong emission from polycyclic aromatic hydrocarbons (PAHs), with the 6.2 um emission feature shifted to 6.3 um and the strongest C-C skeletal-mode feature occuring at 7.9 um instead of at 7.7 um as is often seen. Remarkably, none of the four stars have silicate emission. The strength of the 7.9 um feature varies with respect to the 11.3 um feature among the sources, indicating that we have observed PAHs with a range of ionization fractions. The ionization fraction is higher for systems with hotter and brighter central stars. Two sources, HD 34282 and HD 169142, show emission features from aliphatic hydrocarbons at 6.85 and 7.25 um. The spectrum of HD 141569 shows a previously undetected emission feature at 12.4 um which may be related to the 12.7 um PAH feature. The spectrum of HD 135344, the coolest star in our sample, shows an unusual profile in the 7-9 u...

  5. The Near-Star Environment: Spectropolarimetry of Herbig Ae/Be Stars

    CERN Document Server

    Harrington, D M

    2007-01-01

    The near-star environment around young stars is very dynamic with winds, disks, and outflows. These processes are involved in star and planet formation, and influence the formation and habitability of planets around host stars. Even for the closest young stars, this will not be imaged even after the completion of the next generation of telescopes decades from now and other proxies must be used. The polarization of light across individual spectral lines is such a proxy that contains information about the geometry and density of circumstellar material on these small spatial scales. We have recently built a high-resolution spectropolarimeter (R~13000 to 50000) for the HiVIS spectrograph on the 3.67m AEOS telescope. We used this instrument to monitor several young intermediate-mass stars over many nights. These observations show clear spectropolarimetric signatures typically centered on absorptive components of the spectral lines, with some signatures variable in time. The survey also confirms the large spectrosc...

  6. Photometric and Polarimetric Activity of the Herbig Ae Star VX Cas

    Science.gov (United States)

    Shakhovskoi, D. N.; Rostopchina, A. N.; Grinin, V. P.; Minikulov, N. Kh.

    2003-04-01

    We present the results of our simultaneous photometric and polarimetric observations of the Herbig Ae/Be star VX Cas acquired in 1987 2001. The star belongs to the UX Ori subtype of young variable stars and exhibits a rather low level of photometric activity: only six Algol-like minima with amplitudes ΔV>1m were recorded in 15 years of observations. Two of these minima, in 1998 and 2001, were the deepest in the history of the star’s photometric studies, with V amplitudes of about 2m. In each case, the dimming was accompanied by an increase in the linear polarization in agreement with the law expected for variable circumstellar extinction. The highest V polarization was about 5%. Observations of VX Cas in the deep minima revealed a turnover of the color tracks, typical of stars of this type and due to an increased contribution from radiation scattered in the circumstellar disk. We separated the observed polarization of VX Cas into interstellar (P is) and intrinsic (P in) components. Their position angles differ by approximately 60°, with P is dominating in the bright state and P in dominating during the deep minima. The competition of these two polarization components leads to changes in both the degree and position angle of the polarization during the star’s brightness variations. Generally speaking, in terms of the behavior of the brightness, color indices, and linear polarization, VX Cas is similar to other UX Ori stars studied by us earlier. A number of episodes of photometric and polarimetric activity suggest that, in their motion along highly eccentric orbits, circumstellar gas and dust clouds can enter the close vicinity of the star (and be disrupted there).

  7. Spectroscopic signatures of magnetospheric accretion in Herbig Ae/Be stars. I. The case of HD101412

    CERN Document Server

    Schöller, M; Cahuasqui, J A; Drake, N A; Hubrig, S; Petr-Gotzens, M G; Savanov, I S; Wolff, B; Gonzalez, J F; Mysore, S; Ilyin, I; Jarvinen, S P; Stelzer, B

    2016-01-01

    Models of magnetically-driven accretion and outflows reproduce many observational properties of T Tauri stars. This concept is not well established for the more massive Herbig Ae/Be stars. We intend to examine the magnetospheric accretion in Herbig Ae/Be stars and search for rotational modulation using spectroscopic signatures, in this first paper concentrating on the well-studied Herbig Ae star HD101412. We used near-infrared spectroscopic observations of the magnetic Herbig Ae star HD101412 to test the magnetospheric character of its accretion disk/star interaction. We reduced and analyzed 30 spectra of HD101412, acquired with the CRIRES and X-shooter spectrographs installed at the VLT (ESO, Chile). The spectroscopic analysis was based on the He I lambda 10,830 and Pa gamma lines, formed in the accretion region. We found that the temporal behavior of these diagnostic lines in the near-infrared spectra of HD101412 can be explained by rotational modulation of line profiles generated by accreting gas with a pe...

  8. Spectroscopic signatures of magnetospheric accretion in Herbig Ae/Be stars. I. The case of HD 101412

    Science.gov (United States)

    Schöller, M.; Pogodin, M. A.; Cahuasquí, J. A.; Drake, N. A.; Hubrig, S.; Petr-Gotzens, M. G.; Savanov, I. S.; Wolff, B.; González, J. F.; Mysore, S.; Ilyin, I.; Järvinen, S. P.; Stelzer, B.

    2016-07-01

    Context. Models of magnetically-driven accretion and outflows reproduce many observational properties of T Tauri stars. This concept is not well established for the more massive Herbig Ae/Be stars. Aims: We intend to examine the magnetospheric accretion in Herbig Ae/Be stars and search for rotational modulation using spectroscopic signatures, in this first paper concentrating on the well-studied Herbig Ae star HD 101412. Methods: We used near-infrared spectroscopic observations of the magnetic Herbig Ae star HD 101412 to test the magnetospheric character of its accretion disk/star interaction. We reduced and analyzed 30 spectra of HD 101412, acquired with the CRIRES and X-shooter spectrographs installed at the VLT (ESO, Chile). The spectroscopic analysis was based on the He iλ10 830 and Paγ lines, formed in the accretion region. Results: We found that the temporal behavior of these diagnostic lines in the near-infrared spectra of HD 101412 can be explained by rotational modulation of line profiles generated by accreting gas with a period P = 20.53d±1.68d. The discovery of this period, about half of the magnetic rotation period Pm = 42.076d previously determined from measurements of the mean longitudinal magnetic field, indicates that the accreted matter falls onto the star in regions close to the magnetic poles intersecting the line-of-sight two times during the rotation cycle. We intend to apply this method to a larger sample of Herbig Ae/Be stars. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 087.C-0124(A), 088.C-0218(A,B,C,E), 090.C-0331(A), and 092.C-0126(A).

  9. Magnetism and binarity of the Herbig Ae star V380 Ori

    CERN Document Server

    Alecian, E; Catala, C; Bagnulo, S; Böhm, T; Bouret, J -C; Donati, J -F; Folsom, C P; Grunhut, J; Landstreet, J D

    2009-01-01

    In this paper we report the results of high-resolution circular spectropolarimetric monitoring of the Herbig Ae star V380 Ori, in which we discovered a magnetic field in 2005. A careful study of the intensity spectrum reveals the presence of a cool spectroscopic companion. By modelling the binary spectrum we infer the effective temperature of both stars: $10500\\pm 500$ K for the primary, and $5500\\pm500$ K for the secondary, and we argue that the high metallicity ($[M/H] = 0.5$), required to fit the lines may imply that the primary is a chemically peculiar star. We observe that the radial velocity of the secondary's lines varies with time, while that of the the primary does not. By fitting these variations we derive the orbital parameters of the system. We find an orbital period of $104\\pm5$ d, and a mass ratio ($M_{\\rm P}/M_{\\rm S}$) larger than 2.9. The intensity spectrum is heavily contaminated with strong, broad and variable emission. A simple analysis of these lines reveals that a disk might surround the...

  10. Spectropolarimetry of the H-alpha line in Herbig Ae/Be stars

    CERN Document Server

    Harrington, D M

    2007-01-01

    Using the HiVIS spectropolarimeter built for the Haleakala 3.7m AEOS telescope, we have obtained a large number of high precision spectropolarimetrc observations (284) of Herbig AeBe stars collected over 53 nights totaling more than 300 hours of observing. Our sample of five HAeBe stars: AB Aurigae, MWC480, MWC120, MWC158 and HD58647, all show systematic variations in the linear polarization amplitude and direction as a function of time and wavelength near the H-alpha line. In all our stars, the H-alpha line profiles show evidence of an intervening disk or outflowing wind, evidenced by strong emission with an absorptive component. The linear polarization varies by 0.2% to 1.5% with the change typically centered in the absorptive part of the line profile. These observations are inconsistent with a simple disk-scattering model or a depolarization model which produce polarization changes centered on the emmissive core. We speculate that polarized absorption via optical pumping of the intervening gas may be the c...

  11. A Study of Ro-vibrational OH Emission from Herbig Ae/Be Stars

    CERN Document Server

    Brittain, Sean D; Carr, John S; Ádámkovics, Máté; Reynolds, Nickalas

    2016-01-01

    We present a study of ro-vibrational OH and CO emission from 21 disks around Herbig Ae/Be stars. We find that the OH and CO luminosities are proportional over a wide range of stellar ultraviolet luminosities. The OH and CO line profiles are also similar, indicating that they arise from roughly the same radial region of the disk. The CO and OH emission are both correlated with the far-ultraviolet luminosity of the stars, while the PAH luminosity is correlated with the longer wavelength ultraviolet luminosity of the stars. Although disk flaring affects the PAH luminosity, it is not a factor in the luminosity of the OH and CO emission. These properties are consistent with models of UV-irradiated disk atmospheres. We also find that the transition disks in our sample, which have large optically thin inner regions, have lower OH and CO luminosities than non-transition disk sources with similar ultraviolet luminosities. This result, while tentative given the small sample size, is consistent with the interpretation t...

  12. High-resolution 25 \\mu m imaging of the disks around Herbig Ae/Be stars

    CERN Document Server

    Honda, M; Okamoto, Y K; Kataza, H; Yamashita, T; Miyata, T; Sako, S; Fujiyoshi, T; Sakon, I; Fujiwara, H; Kamizuka, T; Mulders, G D; Lopez-Rodriguez, E; Packham, C; Onaka, T

    2015-01-01

    We imaged circumstellar disks around 22 Herbig Ae/Be stars at 25 \\mu m using Subaru/COMICS and Gemini/T-ReCS. Our sample consists of equal numbers of objects belonging to the two categories defined by Meeus et al. (2001); 11 group I (flaring disk) and II (at disk) sources. We find that group I sources tend to show more extended emission than group II sources. Previous studies have shown that the continuous disk is hard to be resolved with 8 meter class telescopes in Q-band due to the strong emission from the unresolved innermost region of the disk. It indicates that the resolved Q-band sources require a hole or gap in the disk material distribution to suppress the contribution from the innermost region of the disk. As many group I sources are resolved at 25 \\mu m, we suggest that many, not all, group I Herbig Ae/Be disks have a hole or gap and are (pre-)transitional disks. On the other hand, the unresolved nature of many group II sources at 25 \\mu m supports that group II disks have continuous at disk geometr...

  13. NuSTAR AND SWIFT Observations of the Fast Rotating Magnetized White Dwarf AE Aquarii

    Science.gov (United States)

    Kitaguchi, Takao; An, Hongjun; Beloborodov, Andrei M.; Gotthelf, Eric V.; Hayashi, Takayuki; Kaspi, Victoria M.; Rana, Vikram R.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Hailey, Charles J.; Harrison, Fiona A.; Stern, Daniel; Zhang, Will W.

    2014-01-01

    AE Aquarii is a cataclysmic variable with the fastest known rotating magnetized white dwarf (P(sub spin) = 33.08 s). Compared to many intermediate polars, AE Aquarii shows a soft X-ray spectrum with a very low luminosity (LX (is) approximately 10(exp 31) erg per second). We have analyzed overlapping observations of this system with the NuSTAR and the Swift X-ray observatories in 2012 September. We find the 0.5-30 keV spectra to be well fitted by either an optically thin thermal plasma model with three temperatures of 0.75(+0.18 / -0.45), 2.29(+0.96 / -0.82), and 9.33 (+6.07 / -2.18) keV, or an optically thin thermal plasma model with two temperatures of 1.00 (+0.34 / -0.23) and 4.64 (+1.58 / -0.84) keV plus a power-law component with photon index of 2.50 (+0.17 / -0.23). The pulse profile in the 3-20 keV band is broad and approximately sinusoidal, with a pulsed fraction of 16.6% +/- 2.3%. We do not find any evidence for a previously reported sharp feature in the pulse profile.

  14. An Ionized Outflow from AB Aur, a Herbig Ae Star with a Transitional Disk

    CERN Document Server

    Rodriguez, Luis F; Dzib, Sergio A; Ortiz-Leon, Gisela; Loinard, Laurent; Macias, Enrique; Anglada, Guillem

    2014-01-01

    AB Aur is a Herbig Ae star with a transitional disk. Transitional disks present substantial dust clearing in their inner regions, most probably because of the formation of one or more planets, although other explanations are still viable. In transitional objects, accretion is found to be about an order of magnitude smaller than in classical full disks. Since accretion is believed to be correlated with outflow activity, centimeter free-free jets are expected to be present in association with these systems, at weaker levels than in classical protoplanetary (full) systems. We present new observations of the centimeter radio emission associated with the inner regions of AB Aur and conclude that the morphology, orientation, spectral index and lack of temporal variability of the centimeter source imply the presence of a collimated, ionized outflow. The radio luminosity of this radio jet is, however, about 20 times smaller than that expected for a classical system of similar bolometric luminosity. We conclude that c...

  15. Spectroscopic monitoring of the Herbig Ae star HD 104237. II. Non-radial pulsations, mode analysis and fundamental stellar parameters

    CERN Document Server

    Fumel, Aurelie

    2011-01-01

    Herbig Ae/Be stars are intermediate-mass pre-main sequence (PMS) stars showing signs of intense activity and strong stellar winds, whose origin is not yet understood in the frame of current theoretical models of stellar evolution for young stars. The evolutionary tracks of the earlier Herbig Ae stars cross a recently discovered PMS instability strip. Many of these stars exhibit pulsations of delta Scuti type. HD 104237 is a well-known pulsating Herbig Ae star. In this article, we reinvestigated an extensive high-resolution quasi-continuous spectroscopic data set in order to search for very faint indications of non-radial pulsations in the line profile. To do this, we worked on dynamical spectra of equivalent photospheric (LSD) profiles of HD 104237. A 2D Fourier analysis (F2D) was performed of the entire profile and the temporal variation of the central depth of the line was studied with the time-series analysis tools Period04 and SigSpec. We present a mode identification corresponding to the detected dominan...

  16. AN IONIZED OUTFLOW FROM AB AUR, A HERBIG AE STAR WITH A TRANSITIONAL DISK

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez, Luis F.; Zapata, Luis A.; Ortiz-León, Gisela N.; Loinard, Laurent [Centro de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán (Mexico); Dzib, Sergio A. [Max Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Macías, Enrique; Anglada, Guillem, E-mail: l.rodriguez@crya.unam.mx [Instituto de Astrofísica de Andalucía (CSIC), Apartado 3004, E-18080 Granada (Spain)

    2014-09-20

    AB Aur is a Herbig Ae star with a transitional disk. Transitional disks present substantial dust clearing in their inner regions, most probably because of the formation of one or more planets, although other explanations are still viable. In transitional objects, accretion is found to be about an order of magnitude smaller than in classical full disks. Since accretion is believed to be correlated with outflow activity, centimeter free-free jets are expected to be present in association with these systems, at weaker levels than in classical protoplanetary (full) systems. We present new observations of the centimeter radio emission associated with the inner regions of AB Aur and conclude that the morphology, orientation, spectral index, and lack of temporal variability of the centimeter source imply the presence of a collimated, ionized outflow. The radio luminosity of this radio jet is, however, about 20 times smaller than that expected for a classical system of similar bolometric luminosity. We conclude that centimeter continuum emission is present in association with stars with transitional disks, but at levels than are becoming detectable only with the upgraded radio arrays. On the other hand, assuming that the jet velocity is 300 km s{sup –1}, we find that the ratio of mass loss rate to accretion rate in AB Aur is ∼0.1, similar to that found for less evolved systems.

  17. Constraining the wind launching region in Herbig Ae stars: AMBER/VLTI spectroscopy of HD104237

    CERN Document Server

    Tatulli, E; Natta, A; Testi, L

    2006-01-01

    We investigate the origin of the $\\mathrm{Br}\\gamma$ emission of the Herbig Ae star HD104237 on Astronomical Unit (AU) scales. Using AMBER/VLTI at a spectral resolution R=1500 spatially resolve the emission in both the BrGamma line and the adjacent continuum. The visibility does not vary between the continuum and the BrGamma line, even though the line is strongly detected in the spectrum, with a peak intensity 35% above the continuum. This demonstrates that the line and continuum emission have similar size scales. We assume that the K-band continuum excess originates in a ``puffed-up'' inner rim of the circumstellar disk, and discuss the likely origin of BrGamma. We conclude that this emission most likely arises from a compact disk wind, launched from a region 0.2-0.5 AU from the star, with a spatial extent similar to that of the near infrared continuum emission region, i.e, very close to the inner rim location.

  18. Temperaments of young stars: Rapid mass-accretion rate changes in T Tauri and Herbig Ae stars

    CERN Document Server

    Costigan, Gráinne; Scholz, Aleks; Ray, Tom; Testi, Leonardo

    2014-01-01

    Variability in emission lines is a characteristic feature in young stars and can be used as a tool to study the physics of the accretion process. Here we present a study of H{\\alpha} variability in 15 T Tauri and Herbig Ae stars (K7-B2) over a wide range of time windows, from minutes, to hours, to days, and years. We assess the variability using linewidth measurements and the time series of line profiles. All objects show gradual, slow profile changes on time-scales of days. In addition, in three cases there is evidence for rapid variations in H{\\alpha} with typical time-scales of 10 min, which occurs in 10% of the total covered observing time. The mean accretion-rate changes, inferred from the line fluxes,are 0.01-0.07 dex for time-scales of < 1 hour, 0.04-0.4 dex for time-scales of days, and 0.13-0.52 dex for time-scales of years. In Costigan et al. 2012 we derived an upper limit finding that the intermediate (days) variability dominated over longer (years) variability. Here our new results, based on muc...

  19. Polycyclic Aromatic Hydrocarbons in Protoplanetary Disks around Herbig Ae/Be and T Tauri Stars

    Science.gov (United States)

    Seok, Ji Yeon; Li, Aigen

    2017-02-01

    A distinct set of broad emission features at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 μm, is often detected in protoplanetary disks (PPDs). These features are commonly attributed to polycyclic aromatic hydrocarbons (PAHs). We model these emission features in the infrared spectra of 69 PPDs around 14 T Tauri and 55 Herbig Ae/Be stars in terms of astronomical PAHs. For each PPD, we derive the size distribution and the charge state of the PAHs. We then examine the correlations of the PAH properties (i.e., sizes and ionization fractions) with the stellar properties (e.g., stellar effective temperature, luminosity, and mass). We find that the characteristic size of the PAHs tends to correlate with the stellar effective temperature ({T}{eff}) and interpret this as the preferential photodissociation of small PAHs in systems with higher {T}{eff} of which the stellar photons are more energetic. In addition, the PAH size shows a moderate correlation with the red-ward wavelength shift of the 7.7 μm PAH feature that is commonly observed in disks around cool stars. The ionization fraction of PAHs does not seem to correlate with any stellar parameters. This is because the charging of PAHs depends on not only the stellar properties (e.g., {T}{eff}, luminosity) but also their spatial distribution in the disks. The marginally negative correlation between PAH size and stellar age suggests that continuous replenishment of PAHs via the outgassing of cometary bodies and/or the collisional grinding of planetesimals and asteroids is required to maintain the abundance of small PAHs against complete destruction by photodissociation.

  20. Near-infrared interferometric observation of the Herbig Ae star HD144432 with VLTI/AMBER

    CERN Document Server

    Chen, Lei; Wang, Yang; Weigelt, Gerd; Hofmann, Karl-Heinz; Kraus, Stefan; Schertl, Dieter; Lagarde, Stephane; Natta, Antonella; Petrov, Roman; Robbe-Dubois, Sylvie; Tatulli, Eric

    2012-01-01

    We study the sub-AU-scale circumstellar environment of the Herbig Ae star HD144432 with near-infrared (NIR) VLTI/AMBER observations to investigate the structure of its inner dust disk. The interferometric observations were carried out with the AMBER instrument in the H and K band. We interpret the measured H- and K-band visibilities, the near- and mid-infrared visibilities from the literature, and the SED of HD144432 by using geometric ring models and ring-shaped temperature-gradient disk models with power-law temperature distributions. We derived a K-band ring-fit radius of 0.17 \\pm 0.01 AU and an H-band radius of 0.18 \\pm 0.01 AU (for a distance of 145 pc). This measured K-band radius of \\sim0.17 AU lies in the range between the dust sublimation radius of \\sim0.13 AU (predicted for a dust sublimation temperature of 1500 K and gray dust) and the prediction of models including backwarming (\\sim0.27 AU). We found that an additional extended halo component is required in both the geometric and temperature-gradi...

  1. Flaring vs. self-shadowed disks: the SEDs of Herbig Ae/Be stars

    CERN Document Server

    Dullemond, C P

    2004-01-01

    Isolated Herbig Ae stars can be divided into two groups (Meeus et al. 2001): those with an almost flat spectral energy distribution in the mid-infrared (`group I'), and those with a strong decline towards the far-infrared (`group II'). In this paper we show that the group I vs. II distinction can be understood as arising from flaring vs. self-shadowed disks. We show that these two types of disks are natural solutions of the 2-D radiation-hydrostatic structure equations. Disks with high optical depth turn out to be flaring and have a strong far-IR emission, while disks with an optical depth below a certain threshold drop into the shadow of their own puffed-up inner rim and are weak in the far-IR. In spite of not having a directly irradiated surface layer, self-shadowed disks still display dust features in emission, in agreement with observations of group II sources. We propose an evolutionary scenario in which a disk starts out with a flaring shape (group I source), and then goes through the process of grain g...

  2. Spectroscopic Evidence of Sporadic Gas Accretion onto the Herbig AE Stars with Non-Periodic Algol-Type Minima

    Science.gov (United States)

    Kozlova, O. V.; Grinin, V. P.; Rostopchina, A. N.

    We present the results of simultaneous spectroscopic and photometric observations for six isolated Herbig Ae stars with non-periodic Algol-like minima: UX Ori, BF Ori, CQ Tau, SV Cep, VX Gas, and WW Vul. In all cases the Ha line has the profile typical for axially symmetric accretion. In the spectra of five stars (CQ Tau is the exception) the strong He I 5876 Å line has been observed in absorption which is not typical of normal A stars. In three cases: UX Ori, VX Cas, and WW Vul, variability of this line is found. We did not observe any correlation between the strength of this line and the brightness of the stars. These observational facts are considered as evidence for gas accretion, which is probably an important property of young stars with non-periodic Algol-type minima.

  3. Investigation of the magnetic field characteristics of Herbig Ae/Be stars: Discovery of the pre-main sequence progenitors of the magnetic Ap/Bp stars

    CERN Document Server

    Wade, G A; Bagnulo, S; Landstreet, J D; Mason, E; Silvester, J; Alecian, E; Böhm, T; Bouret, J C; Catala, C; Donati, J F; Folsom, C; Bale, K

    2006-01-01

    We are investigating the magnetic characteristics of pre-main sequence Herbig Ae/Be stars, with the aim of (1) understanding the origin and evolution of magnetism in intermediate-mass stars, and (2) exploring the influence of magnetic fields on accretion, rotation and mass-loss at the early stages of evolution of A, B and O stars. We have begun by conducting 2 large surveys of Herbig Ae/Be stars, searching for direct evidence of photospheric magnetic fields via the longitudinal Zeeman effect. From observations obtained using FORS1 at the ESO-VLT and ESPaDOnS at the Canada-France-Hawaii Telescope, we report the confirmed detection of magnetic fields in 4 pre-main sequence A- and B-type stars, and the apparent (but as yet unconfirmed) detection of fields in 2 other such stars. We do not confirm the detection of magnetic fields in several stars reported by other authors to be magnetic: HD 139614, HD 144432 or HD 31649. One of the most evolved stars in the detected sample, HD 72106A, shows clear evidence of stron...

  4. Line Identifications and Preliminary Synthesis of High-resolution Infrared Spectra of CP and Herbig Ae Stars

    Science.gov (United States)

    Cowley, Charles R.; Castelli, F.; Hubrig, S.; Wolff, B.; Elkin, V.

    2012-01-01

    We report on surveys of infrared spectra of chemically peculiar and Herbig Ae stars based on CRIRES (Kaufl, et al. SPIE, 5492, 1218 2004). We discuss the magnetic CP stars Gamma Equ and HD 154708, and multiple-phase observations of the Herbig Ae star HD 101412. The Be star HR 4537 and HgMn HR 6620 were also examined. The primary emphasis of the present work is on line identifications primarily in four regions, 1065-1091, 1084-1109,1550-1587, and 2276-2313nm (with order gaps). Observations were reduced with recipes available from the ESO CRIRES data reduction pipeline. Wavelength calibration is determined from daytime ThAr arc lamp exposures. Generally speaking, this is not rich in atomic lines. The strongest features are the Paschen line P6 (1093.81nm), and He I (108.30nm). The latter shows phase variations indicative of a more complex magnetic field than that of a pure dipole. No individual molecular lines were found in these early stars, though CO emission from circumstellar material is likely present in HR 4537 and HD 101412. We used atomic line lists from Kurucz's site (kurucz.harvard.edu) and VALD (http://vald.astro.univie.ac.at/ cf. Kupka et al. 1999, A&AS, 138, 119), supplemented by Outred (J. Phys. Chem. Ref. Data 7, 1, 1978). The following spectra were identified in Gamma Equ: C I, Si I, Ca I, Mg I, II, Cr I, Fe I, Sr II, and Ce III (1584.75nm). The Ap star spectra show broad Zeeman patterns compatible with published models and field strengths. Synthetic calculations used SYNTHE and SYNTHMAG (Piskunov N. E., 1999, in Astrophys. Space Sci. Library Vol. 243, Solar polarization. Kluwer, p 515). The γ Equ model is from Heiter et al. (2002, A&A, 392, 619). and the line list from VALD.

  5. Effect of Photodesorption on Snow Line at the Surface of Optically Thick Circumstellar Disks around Herbig Ae/Be Stars

    CERN Document Server

    Oka, Akinori; Nakamoto, Taishi; Honda, Mitsuhito

    2012-01-01

    We investigate the effect of photodesorption on the snow line position at the surface of a protoplanetary disk around a Herbig Ae/Be star, motivated by the detection of water ice particles at the surface of the disk around HD142527 by Honda et al. For this aim, we obtain the density and temperature structure in the disk with a 1+1D radiative transfer and determine the distribution of water ice particles in the disk by the balance between condensation, sublimation, and photodesorption. We find that photodesorption induced by the far-ultraviolet radiation from the central star depresses the ice-condensation front toward the mid-plane and pushes the surface snow line outward significantly when the stellar effective temperature exceeds a certain critical value. This critical effective temperature depends on the stellar luminosity and mass, the water abundance in the disk, and the yield of photodesorption. We present an approximate analytic formula for the critical temperature. We separate Herbig Ae/Be stars into ...

  6. PAH emission from Herbig AeBe stars: Do hydrocarbons in proto-planetary disks have a unique aroma?

    Science.gov (United States)

    Keller, Luke; Sloan, Greg

    2008-03-01

    Over half of the intermediate-mass young stellar objects in the Galaxy (e.g. Herbig AeBe stars or HAeBe) have high-contrast emission in the mid-infrared spectral features of polycyclic aromatic hydrocarbons (PAHs) above the continuum produced by thermal emission from dust in the circumstellar disks. We have examined the PAH emission in detail for a sample of 19 HAeBe stars observed with the Spitzer IRS as part of the IRS Disks GTO program. Even with this relatively small sample, we have identified some trends that, should they survive in a larger sample of HAeBe stars, will allow us to infer large-scale disk geometry (both inner and outer) and the degree of photo-processing of organic molecular material in HAeBe disks. The bottom line of our work thus far is that HAeBe apparently have distinctive PAH spectra among the many other astronomical environments that are characterized by strong PAH emission. We therefore propose to apply our spectral analysis methods to an additional 57 HAeBe observed with the IRS and currently (or soon to be) available in the Spitzer archive. Our total sample of 76 HAeBe stars will allow closer scrutiny of the trends that we have identified in our empirical study and will also be the subject of a detailed disk modeling effort that will include the PAH emission.

  7. A spectroscopic survey of Herbig Ae/Be stars with X-Shooter II: Accretion diagnostic lines

    CERN Document Server

    Fairlamb, John R; Mendigutia, Ignacio; Ilee, John D; Ancker, Mario E van den

    2016-01-01

    The Herbig Ae/Be stars (HAeBes) allow an exploration of the properties of Pre-Main Sequence(PMS) stars above the low-mass range ($8{\\rm\\thinspace M_{\\odot}}$). This paper is the second in a series exploring accretion in 91 HAeBes with Very Large Telescope/X-shooter spectra. Equivalent width measurements are carried out on 32 different lines, spanning the UV to NIR, in order to obtain their line luminosities. The line luminosities were compared to accretion luminosities, which were determined directly from measurements of an UV-excess. When detected, emission lines always demonstrate a correlation with the accretion luminosity, regardless of detection frequency. The average relationship between accretion luminosity and line luminosity is found to be ${\\thinspace L_{\\rm acc}}\\propto{\\thinspace L_{\\rm line}}^{1.16 \\pm 0.15}$. This is in agreement with the findings in Classical T Tauri stars, although the HAeBe relationship is generally steeper, particularly towards the Herbig Be mass range. Since all observed li...

  8. Probing the Structure of the Accretion Region in a Sample of Magnetic Herbig Ae/Be Stars

    CERN Document Server

    Pogodin, M A; Drake, N A; Hubrig, S; Schoeller, M; Petr-Gotzens, M; Franco, G A P; Lopes, D F; Kozlova, O V; Wolff, B; Gonzalez, J F; Carroll, T A; Mysore, S

    2014-01-01

    We present the results of a study of the temporal behaviour of several diagnostic lines formed in the region of the accretion-disk/star interaction in the three magnetic Herbig Ae stars HD101412, HD104237, and HD190073. More than 100 spectra acquired with the ISAAC, X-shooter, and CRIRES spectrographs installed at the VLT-8m telescope (ESO, Chile), as well as at other observatories (OHP, Crimean AO) were analyzed. The spectroscopic data were obtained in the He I lambda10830, Pa gamma and He I lambda5876 lines. We found that the temporal behaviour of the diagnostic lines in the spectra of all program stars can be widely explained by a rotational modulation of the line profiles generated by a local accretion flow. This result is in good agreement with the predictions of the magnetospheric accretion model. For the first time, the rotation period of HD104237 (P_rot = 5.37+-0.03 days), as well as the inclination angle (i = 21+-4deg) were determined. Additional analysis of the HARPSpol spectra of HD104237 and HD190...

  9. A spectroscopic survey of Herbig Ae/Be stars with X-Shooter - II. Accretion diagnostic lines

    Science.gov (United States)

    Fairlamb, J. R.; Oudmaijer, R. D.; Mendigutia, I.; Ilee, J. D.; van den Ancker, M. E.

    2017-02-01

    The Herbig Ae/Be stars (HAeBes) allow an exploration of the properties of pre-main-sequence(PMS) stars above the low-mass range (8 M_{⊙}). This paper is the second in a series exploring accretion in 91 HAeBes with Very Large Telescope/X-shooter spectra. Equivalent width measurements are carried out on 32 different lines, spanning the UV (ultraviolet) to NIR (near infrared), in order to obtain their line luminosities. The line luminosities were compared to accretion luminosities that were determined directly from measurements of a UV excess. When detected, emission lines always demonstrate a correlation with the accretion luminosity, regardless of detection frequency. The average relationship between accretion luminosity and line luminosity is found to be L_acc ∝ L_line1.16 ± 0.15. This is in agreement with the findings in Classical T Tauri stars, although the HAeBe relationship is generally steeper, particularly towards the Herbig Be mass range. Since all observed lines display a correlation with the accretion luminosity, all of them can be used as accretion tracers. This has increased the number of accretion diagnostic lines in HAeBes 10-fold. However, questions still remain on the physical origin of each line, which may not be due to accretion.

  10. Brackett γ radiation from the inner gaseous accretion disk, magnetosphere, and disk wind region of Herbig AeBe stars

    Science.gov (United States)

    Tambovtseva, L. V.; Grinin, V. P.; Weigelt, G.

    2016-05-01

    Various disk and outflow components such as the magnetosphere, the disk wind, the gaseous accretion disk, and other regions may contribute to the hydrogen line emission of young Herbig AeBe stars. Non-LTE modeling was performed to show the influence of the model parameters of each emitting region on the intensity and shape of the Brγ line profile, to present the spatial brightness distribution of each component, and to compare the contribution of each component to the total line emission. The modeling shows that the disk wind is the dominant contributor to the Brγ line rather than the magnetosphere and inner gaseous accretion disk. The contribution of the disk wind region to the Hα line is also considered.

  11. Linear spectropolarimetry across the optical spectrum of Herbig Ae/Be stars

    CERN Document Server

    Ababakr, K M; Vink, J S

    2016-01-01

    We present the results of spectropolarimetric observations of 12 Herbig Ae/Be objects. Our data have the largest spectropolarimetric wavelength coverage, 4560 {\\AA} to 9480 {\\AA}, published to date. A change in linear polarisation across the H{\\alpha} line, is detected in all objects. Such a line effect reveals the fact that stellar photons are scattered off free electrons that are not distributed in a spherically symmetric volume, suggesting the presence of small disks around these accreting objects. Thanks to the large wavelength coverage, we can report that H{\\alpha} is the spectral line in the optical wavelength range that is most sensitive to revealing deviations from spherical symmetry, and the one most likely to show a line effect across the polarisation in such cases. Few other spectral lines display changes in polarisation across the line. In addition, H{\\alpha} is the only line which shows an effect across its absorption component in some sources. We present a scenario explaining this finding and de...

  12. HIGH-RESOLUTION 25 μM IMAGING OF THE DISKS AROUND HERBIG AE/BE STARS

    Energy Technology Data Exchange (ETDEWEB)

    Honda, M. [Department of Mathematics and Physics, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293 (Japan); Maaskant, K. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Okamoto, Y. K. [Institute of Astrophysics and Planetary Sciences, Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512 (Japan); Kataza, H. [Department of Infrared Astrophysics, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Yamashita, T. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Miyata, T.; Sako, S.; Kamizuka, T. [Institute of Astronomy, School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Fujiyoshi, T.; Fujiwara, H. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A’ohoku Place, Hilo, Hawaii 96720 (United States); Sakon, I.; Onaka, T. [Department of Astronomy, School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Mulders, G. D. [Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721 (United States); Lopez-Rodriguez, E.; Packham, C. [Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 (United States)

    2015-05-10

    We imaged circumstellar disks around 22 Herbig Ae/Be stars at 25 μm using Subaru/COMICS and Gemini/T-ReCS. Our sample consists of an equal number of objects from each of the two categories defined by Meeus et al.; 11 group I (flaring disk) and II (flat disk) sources. We find that group I sources tend to show more extended emission than group II sources. Previous studies have shown that the continuous disk is difficult to resolve with 8 m class telescopes in the Q band due to the strong emission from the unresolved innermost region of the disk. This indicates that the resolved Q-band sources require a hole or gap in the disk material distribution to suppress the contribution from the innermost region of the disk. As many group I sources are resolved at 25 μm, we suggest that many, but not all, group I Herbig Ae/Be disks have a hole or gap and are (pre-)transitional disks. On the other hand, the unresolved nature of many group II sources at 25 μm supports the idea that group II disks have a continuous flat disk geometry. It has been inferred that group I disks may evolve into group II through the settling of dust grains into the mid-plane of the protoplanetary disk. However, considering the growing evidence for the presence of a hole or gap in the disk of group I sources, such an evolutionary scenario is unlikely. The difference between groups I and II may reflect different evolutionary pathways of protoplanetary disks.

  13. Accretion-related properties of Herbig Ae/Be stars. Comparison with T Tauris

    CERN Document Server

    Mendigutía, I; Montesinos, B; Eiroa, C; Meeus, G; Merín, B; Oudmaijer, R D

    2012-01-01

    We look for trends relating the mass accretion rate (Macc) and the stellar ages (t), spectral energy distributions (SEDs), and disk masses (Mdisk) for a sample of 38 HAeBe stars, comparing them to analogous correlations found for classical T Tauri stars. Our goal is to shed light on the timescale and physical processes that drive evolution of intermediate-mass pre-main sequence objects. Macc shows a dissipation timescale \\tau = 1.3^{+1.0}_{-0.5} Myr from an exponential law fit, while a power law yields Macc(t) \\propto t^{-\\eta}, with \\eta = 1.8^{+1.4}_{-0.7}. This result is based on our whole HAeBe sample (1-6 Msun), but the accretion rate decline most probably depends on smaller stellar mass bins. The near-IR excess is higher and starts at shorter wavelengths (J and H bands) for the strongest accretors. Active and passive disks are roughly divided by 2 x 10^{-7} Msun/yr. The mid-IR excess and the SED shape from the Meeus et al. classification are not correlated with Macc. We find Macc \\propto Mdisk^{1.1 +- 0...

  14. Herbig Ae/Be candidate stars in the innermost Galactic disk: Quartet cluster

    CERN Document Server

    Yasui, Chikako; Hamano, Satoshi; Kondo, Sohei; Izumi, Natsuko; Saito, Masao; Tokunaga, Alan T

    2016-01-01

    In order to investigate the Galactic-scale environmental effects on the evolution of protoplanetary disks, we explored the near-infrared (NIR) disk fraction of the Quartet cluster, which is a young cluster in the innermost Galactic disk at the Galactocentric radius Rg ~ 4 kpc. Because this cluster has a typical cluster mass of ~10^3 M_sun as opposed to very massive clusters, which have been observed in previous studies (>10^4 M_sun), we can avoid intra-cluster effects such as strong UV field from OB stars. Although the age of the Quartet is previously estimated to be 3-8 Myr old, we find that it is most likely ~3-4.5 Myr old. In moderately deep JHK images from the UKIDSS survey, we found eight HAeBe candidates in the cluster, and performed K-band medium-resolution ($R \\equiv \\Delta \\lambda / \\lambda ~ 800$) spectroscopy for three of them with the Subaru 8.2 m telescope. These are found to have both Br\\gamma absorption lines as well as CO bandhead emission, suggesting that they are HAeBe stars with protoplanet...

  15. Few Skewed Disks Found in First Closure-Phase Survey of Herbig Ae/Be stars

    CERN Document Server

    Monnier, J D; Millan-Gabet, R; Traub, W; Schloerb, F P; Pedretti, E; Benisty, M; Carleton, N P; Haguenauer, P; Kern, P; Labeye, P; Lacasse, M G; Malbet, F; Perraut, K; Pearlman, M; Zhao, M

    2006-01-01

    Using the 3-telescope IOTA interferometer on Mt. Hopkins, we report results from the first near-infrared (lambda=1.65 mu) closure-phase survey of Young Stellar Objects (YSOs). These closure phases allow us to unambiguously detect departures from centrosymmetry (i.e., skew) in the emission pattern from YSO disks on the scale of ~4 milliarcseconds, expected from generic ``flared disk'' models. Six of fourteen targets showed small, yet statistically-significant, non-zero closure phases, with largest values from the young binary system MWC 361-A and the (pre-main sequence?) Be star HD 45677. Our observations are quite sensitive to the vertical structure of the inner disk and we confront the predictions of the ``puffed-up inner wall'' models of Dullemond, Dominik, and Natta (DDN). Our data support disks models with curved inner rims because the expected emission appear symmetrically-distributed around the star over a wide range of inclination angles. In contrast, our results are incompatible with the models posses...

  16. Candidate Water Vapor Lines to Locate the H2O Snowline through High-dispersion Spectroscopic Observations. II. The Case of a Herbig Ae Star

    Science.gov (United States)

    Notsu, Shota; Nomura, Hideko; Ishimoto, Daiki; Walsh, Catherine; Honda, Mitsuhiko; Hirota, Tomoya; Millar, T. J.

    2017-02-01

    Observationally measuring the location of the {{{H}}}2{{O}} snowline is crucial for understanding planetesimal and planet formation processes, and the origin of water on Earth. In disks around Herbig Ae stars (T * ∼ 10,000 K, M * ≳ 2.5M ⊙), the position of the {{{H}}}2{{O}} snowline is farther from the central star compared with that around cooler and less massive T Tauri stars. Thus, the {{{H}}}2{{O}} emission line fluxes from the region within the {{{H}}}2{{O}} snowline are expected to be stronger. In this paper, we calculate the chemical composition of a Herbig Ae disk using chemical kinetics. Next, we calculate the {{{H}}}2{{O}} emission line profiles and investigate the properties of candidate water lines across a wide range of wavelengths (from mid-infrared to submillimeter) that can locate the position of the {{{H}}}2{{O}} snowline. Those lines identified have small Einstein A coefficients (∼ {10}-6{--}{10}-3 s‑1) and relatively high upper-state energies (∼1000 K). The total fluxes tend to increase with decreasing wavelengths. We investigate the possibility of future observations (e.g., ALMA, SPICA/SMI-HRS) locating the position of the {{{H}}}2{{O}} snowline. Since the fluxes of those identified lines from Herbig Ae disks are stronger than those from T Tauri disks, the possibility of a successful detection is expected to increase for a Herbig Ae disk.

  17. Gas and dust mass in the disk around the Herbig Ae star HD169142

    CERN Document Server

    Panić, Olja; Wilner, David; Qi, Chunhua

    2008-01-01

    We investigate the physical structure of the gas component of the disk around the pre-main-sequence star HD169142. The 13CO and C18O J=2-1 line emission is observed from the disk with 1.4'' resolution using the Submillimeter Array. We adopt the disk physical structure derived from a model which fits the spectral energy distribution of HD169142. We obtain the full three-dimensional information on the CO emission with the aid of a molecular excitation and radiative transfer code. This information is used for the analysis of our observations and previous 12CO J=2-1 and 1.3 mm continuum data. The disk is in Keplerian rotation and seen at an inclination close to 13 deg from face-on. We conclude that the regions traced by different CO isotopologues are distinct in terms of their vertical location within the disk, their temperature and their column densities. With the given disk structure, we find that freeze-out is not efficient enough to remove a significant amount of CO from gas phase. Both observed lines match t...

  18. On the interplay between flaring and shadowing in disks around Herbig Ae/Be stars

    CERN Document Server

    Acke, B; Ancker, M van den; Bouwman, J; Ochsendorf, B; Juhasz, A; Waters, R

    2009-01-01

    Based on the SED, Herbig stars have been categorized into two observational groups, reflecting their overall disk structure: group I members have disks with a higher degree of flaring than their group II counterparts. We investigate the 5-35 um Spitzer IRS spectra of a sample of 13 group I sources and 20 group II sources. We focus on the continuum emission to study the underlying disk geometry. We have determined the [30/13.5] and [13.5/7] continuum flux ratios. The 7-um flux excess with respect to the stellar photosphere is measured, as a marker for the strength of the near-IR emission produced by the inner disk. We have compared our data to self-consistent passive-disk model spectra, for which the same quantities were derived. We confirm the literature result that the difference in continuum emission between group I and II sources can largely be explained by a different amount of small dust grains. However, we report a strong correlation between the [30/13.5] and [13.5/7] flux ratios for Meeus group II sour...

  19. AE AURIGAE: FIRST DETECTION OF NON-THERMAL X-RAY EMISSION FROM A BOW SHOCK PRODUCED BY A RUNAWAY STAR

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Santiago, J.; Pereira, V.; De Castro, E. [Dpto. de Astrofisica y CC. de la Atmosfera, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Miceli, M.; Bonito, R. [Dipartimento di Fisica, Universita di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy); Del Valle, M. V.; Romero, G. E. [Instituto Argentino de Radioastronomia (IAR), CCT La Plata (CONICET), C.C.5, 1894 Villa Elisa, Buenos Aires (Argentina); Albacete-Colombo, J. F. [Centro Universitario Regional Zona Atlantica (CURZA), Universidad Nacional del COMAHUE, Monsenor Esandi y Ayacucho, 8500 Viedma, Rio Negro (Argentina); Damiani, F. [INAF-Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy)

    2012-09-20

    Runaway stars produce shocks when passing through interstellar medium at supersonic velocities. Bow shocks have been detected in the mid-infrared for several high-mass runaway stars and in radio waves for one star. Theoretical models predict the production of high-energy photons by non-thermal radiative processes in a number sufficiently large to be detected in X-rays. To date, no stellar bow shock has been detected at such energies. We present the first detection of X-ray emission from a bow shock produced by a runaway star. The star is AE Aur, which was likely expelled from its birthplace due to the encounter of two massive binary systems and now is passing through the dense nebula IC 405. The X-ray emission from the bow shock is detected at 30'' northeast of the star, coinciding with an enhancement in the density of the nebula. From the analysis of the observed X-ray spectrum of the source and our theoretical emission model, we confirm that the X-ray emission is produced mainly by inverse Compton upscattering of infrared photons from dust in the shock front.

  20. Multi-Epoch Detections of Water Ice Absorption in Edge-on Disks around Herbig Ae Stars: PDS 144N and PDS 453

    CERN Document Server

    Terada, Hiroshi

    2016-01-01

    We report the multi-epoch detections of the water ice in 2.8-4.2 micron spectra of two Herbig Ae stars, PDS 144N (A2 IVe) and PDS 453 (F2 Ve), which have an edge-on circumstellar disk. The detected water ice absorption is found to originate from their protoplanetary disks. The spectra show a relatively shallow absorption of water ice around 3.1 micron for both objects. The optical depths of the water ice absorption are ~0.1 and ~0.2 for PDS 144N and PDS 453, respectively. Compared to the water ice previously detected in low-mass young stellar objects with an edge-on disk with a similar inclination angle, these optical depths are significantly lower. It suggests that stronger UV radiation from the central stars effectively decreases the water ice abundance around the Herbig Ae stars through photodesorption. The water ice absorption in PDS 453 shows a possible variation of the feature among the six observing epochs. This variation could be due to a change of absorption materials passing through our line-of-sigh...

  1. AE 941.

    Science.gov (United States)

    2004-01-01

    AE 941 [Arthrovas, Neoretna, Psovascar] is shark cartilage extract that inhibits angiogenesis. AE 941 acts by blocking the two main pathways that contribute to the process of angiogenesis, matrix metalloproteases and the vascular endothelial growth factor signalling pathway. When initial development of AE 941 was being conducted, AEterna assigned the various indications different trademarks. Neovastat was used for oncology, Psovascar was used for dermatology, Neoretna was used for ophthalmology and Arthrovas was used for rheumatology. However, it is unclear if these trademarks will be used in the future and AEterna appears to only be using the Neovastat trademark in its current publications regardless of the indication. AEterna Laboratories signed commercialisation agreements with Grupo Ferrer Internacional SA of Spain and Medac GmbH of Germany in February 2001. Under the terms of the agreement, AEterna has granted exclusive commercialisation and distribution rights to AE 941 in oncology to Grupo Ferrer Internacional for the Southern European countries of France, Belgium, Spain, Greece, Portugal and Italy. It also has rights in Central and South America. Medac GmbH will have marketing rights in Germany, the UK, Scandinavia, Switzerland, Austria, Ireland, the Netherlands and Eastern Europe. In October 2002, AEterna Laboratories announced that it had signed an agreement with Australian healthcare products and services company Mayne Group for marketing AE 941 (as Neovastat) in Australia, New Zealand, Canada and Mexico. In March 2003, AEterna Laboratories announced it has signed an agreement with Korean based LG Life Sciences Ltd for marketing AE 941 (as Neovastat) in South Korea. The agreement provides AEterna with upfront and milestone payments, as well as a return on manufacturing and sales of AE 941. AEterna Laboratories had granted Alcon Laboratories an exclusive worldwide licence for AE 941 for ophthalmic products. However, this licence has been terminated. In

  2. Revealing the sub-AU asymmetries of the inner dust rim in the disk around the Herbig Ae star R CrA

    CERN Document Server

    Kraus, S; Malbet, F; Meilland, A; Natta, A; Schertl, D; Stee, P; Weigelt, G

    2009-01-01

    Models predict that in the innermost AU of the disk around Herbig Ae/Be star, the dust disk forms a "puffed-up" inner rim, which should result in a strongly asymmetric brightness distribution for disks seen under intermediate inclination. Using the VLTI/AMBER long-baseline interferometer, we obtained 24 near-infrared (H- and K-band) spectro-interferometric observations on the Herbig Ae star R CrA. In the derived visibility function, we detect the signatures of an extended (25 mas) and a compact component (5.8 mas), with the compact component contributing about 2/3 of the total flux. The brightness distribution is highly asymmetric, as indicated by the strong closure phases (up to 40 deg) and the detected position angle dependence of the visibilities and closure phases. To interpret these asymmetries, we employ geometric as well as physical models, including a binary model, a skewed ring model, and a puffed-up inner rim model with a vertical or curved rim shape. Our curved puffed-up rim model can reasonably we...

  3. A HST study of the environment of the Herbig Ae/Be star LkHa 233 and its bipolar jet

    CERN Document Server

    Melnikov, Stanislav Yu; Eislöffel, Jochen; Bacciotti, Francesca; Locatelli, Ugo; Ray, Thomas P

    2008-01-01

    We present the results of HST/STIS and WFPC2 observations of LkHa 233 and its environment. LkHa233 is a Herbig Ae/Be star with a collimated bipolar jet. We investigate optical forbidden lines along the LkHa 233 jet to determine physical parameters of this jet (electron density n_e, hydrogen ionisation fraction x_e, electron temperature T_e, and mass density n_H). The knowledge of these parameters allows us a direct comparison of a jet from a Herbig star with those from T Tauri stars. The WFPC2 images in broad-band filters clearly show a dark lane caused either by a circumstellar disk or a dust torus. In the blueshifted lobe, n_e is close to or above the critical density for [SII] lines (2.5x10^4 cm^-3) in the first arcsecond and decreases with distance from the source. The ionisation x_e~0.2-0.6 gently rises for the first 500 AU of the flow and shows two re-ionisation events further away from the origin. The T_e varies along the flow between 10^4 K and 3x10^4 K. The (radial) outflow velocities are ~ 80-160 km...

  4. High-resolution Br-gamma spectro-interferometry of the transitional Herbig Ae/Be star HD 100546: a Keplerian gaseous disc inside the inner rim

    CERN Document Server

    Mendigutía, I; Oudmaijer, R D; Fairlamb, J R; Carciofi, A C; Ilee, J D; Vieira, R G

    2015-01-01

    We present spatially and spectrally resolved Br-gamma emission around the planet-hosting, transitional Herbig Ae/Be star HD 100546. Aiming to gain insight into the physical origin of the line in possible relation to accretion processes, we carried out Br-gamma spectro-interferometry using AMBER/VLTI from three different baselines achieving spatial and spectral resolutions of 2-4 mas and 12000. The Br-gamma visibility is larger than that of the continuum for all baselines. Differential phases reveal a shift between the photocentre of the Br-gamma line -displaced 0.6 mas (0.06 au at 100 pc) NE from the star- and that of the K-band continuum emission -displaced 0.3 mas NE from the star. The photocentres of the redshifted and blueshifted components of the Br-gamma line are located NW and SE from the photocentre of the peak line emission, respectively. Moreover, the photocentre of the fastest velocity bins within the spectral line tends to be closer to that of the peak emission than the photocentre of the slowest ...

  5. Dynamics of the circumstellar gas in the Herbig Ae stars BF Orionis, SV Cephei, WW Vulpeculae and XY Persei

    CERN Document Server

    Mora, A; Natta, A; Grady, C A; De Winter, D; Davies, J K; Ferlet, R; Harris, A W; Miranda, L F; Montesinos, B; Oudmaijer, R D; Palacios, J; Quirrenbach, Andreas G; Rauer, H; Alberdi, A; Cameron, A; Deeg, H J; Garzón, F; Horne, K; Merin, B; Penny, A; Schneider, J; Solano, E; Tsapras, Y; Wesselius, P R

    2004-01-01

    We present high resolution (lambda / Delta_lambda = 49000) echelle spectra of the intermediate mass, pre-main sequence stars BF Ori, SV Cep, WW Wul and XY Per. The spectra cover the range 3800-5900 angstroms and monitor the stars on time scales of months and days. All spectra show a large number of Balmer and metallic lines with variable blueshifted and redshifted absorption features superimposed to the photospheric stellar spectra. Synthetic Kurucz models are used to estimate rotational velocities, effective temperatures and gravities of the stars. The best photospheric models are subtracted from each observed spectrum to determine the variable absorption features due to the circumstellar gas; those features are characterized in terms of their velocity, v, dispersion velocity, Delta v, and residual absorption, R_max. The absorption components detected in each spectrum can be grouped by their similar radial velocities and are interpreted as the signature of the dynamical evolution of gaseous clumps with, in m...

  6. Application of the Baade-Wesselink method to a pulsating cluster Herbig Ae star: H254 in IC348

    CERN Document Server

    Ripepi, V; Marconi, M; Catanzaro, G; Claudi, R; Daszyńska-Daszkiewicz, J; Palla, F; Leccia, S; Bernabei, S

    2013-01-01

    In this paper we present new photometric and radial velocity data for the PMS $\\delta$ Sct star H254, member of the young cluster IC 348. Photometric V,R$_C$,I$_C$ light curves were obtained at the Loiano and Asiago telescopes. The radial velocity data was acquired by means of the SARG@TNG spectrograph. High-resolution spectroscopy allowed us to derive precise stellar parameters and the chemical composition of the star, obtaining: T$_{\\rm eff}$\\,=\\,6750\\,$\\pm$\\,150 K; $\\log g$\\,=\\,4.1\\,$\\pm$\\,0.4 dex; [Fe/H]=-0.07$\\pm$0.12 dex. Photometric and spectroscopic data were used to estimate the total absorption in the $V$ band A$_{\\rm V}$=2.06$\\pm$0.05 mag, in agreement with previous estimates. We adopted the technique of the difference in phase and amplitude between different photometric bands and radial velocities to verify that H254 is (definitely) pulsating in a radial mode. This occurrence allowed us to apply the CORS realization of the Baade--Wesselink method to obtain a value for the linear radius of H254 equ...

  7. The structure of disks around Herbig Ae/Be stars as traced by CO ro-vibrational emission

    CERN Document Server

    van der Plas, G; Waters, L B F M; Dominik, C

    2014-01-01

    We study the emission and absorption of CO ro-vibrational lines in the spectra of intermediate mass pre-main-sequence stars with the aim to determine both the spatial distribution of the CO gas and its physical properties. We also aim to correlate CO emission properties with disk geometry. Using high-resolution spectra containing fundamental and first overtone CO ro-vibrational emission, observed with CRIRES on the VLT, we probe the physical properties of the circumstellar gas by studying its kinematics and excitation conditions. We detect and spectrally resolve CO fundamental ro-vibrational emission in 12 of the 13 stars observed, and in two cases in absorption. Keeping in mind that we studied a limited sample, we find that the physical properties and spatial distribution of the CO gas correlate with disk geometry. Flaring disks show highly excited CO fundamental emission up to v$_u$ = 5, while self-shadowed disks show CO emission that is not as highly excited. Rotational temperatures range between ~250-2000...

  8. A 30 AU radius CO gas hole in the disk around the Herbig Ae star Oph IRS 48

    CERN Document Server

    Brown, Joanna M; Pontoppidan, Klaus M; van Dishoeck, Ewine F

    2011-01-01

    The physical processes leading to the disappearance of disks around young stars are not well understood. A subclass of transitional disks, the so-called cold disks with large inner dust holes, provide a crucial laboratory for studying disk dissipation processes. IRS 48 has a 30 AU radius hole previously measured from dust continuum imaging at 18.7 micron. Using new optical spectra, we determine that IRS 48 is a pre-main sequence A0 star. In order to characterize this disk's gas distribution, we obtained AO-assisted VLT CRIRES high resolution (R ~100,000) spectra of the CO fundamental rovibrational band at 4.7 micron. All CO emission, including that from isotopologues and vibrationally excited molecules, is off-source and peaks at 30 AU. The gas is thermally excited to a rotational temperature of 260 K and is also strongly UV pumped, showing a vibrational excitation temperature of ~5000 K. We model the kinematics and excitation of the gas and posit that the CO emission arises from the dust hole wall. Prior ima...

  9. DISCOVERY OF A TWO-ARMED SPIRAL STRUCTURE IN THE GAPPED DISK AROUND HERBIG Ae STAR HD 100453

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Kevin; Apai, Daniel [Department of Astronomy/Steward Observatory, The University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Kasper, Markus [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Robberto, Massimo, E-mail: kwagner@as.arizona.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2015-11-01

    We present Very Large Telescope (VLT)/SPHERE adaptive optics imaging in the Y-, J-, H-, and K-bands of the HD 100453 system and the discovery of a two-armed spiral structure in a disk extending to 0.″37 (∼42 AU) from the star, with highly symmetric arms to the northeast and southwest. Inside of the spiral arms, we resolve a ring of emission from 0.″18 to 0.″25 (∼21–29 AU). By assuming that the ring is intrinsically circular we estimate an inclination of ∼34° from face on. We detect dark crescents on opposite sides (NW and SE) that begin at 0.″18 and continue to radii smaller than our inner working angle of 0.″15, which we interpret as the signature of a gap at ≲21 AU that has likely been cleared by forming planets. We also detect the ∼120 AU companion HD 100453 B, and by comparing our data to 2003 Hubble Space Telescope and VLT/NACO images we estimate an orbital period of ∼850 year. We discuss what implications the discovery of the spiral arms and finer structures of the disk may have on our understanding of the possible planetary system in HD 100453 and how the morphology of this disk compares to other related objects.

  10. The compact H$\\alpha$ emitting regions of the Herbig Ae/Be stars HD 179218 and HD 141569 from CHARA spectro-interferometry

    CERN Document Server

    Mendigutía, I; Mourard, D; Muzerolle, J

    2016-01-01

    This work presents CHARA/VEGA H$\\alpha$ spectro-interferometry (R ~ 6000, and $\\lambda$/2B ~ 1 mas) of HD 179218 and HD 141569, doubling the sample of Herbig Ae/Be (HAeBe) stars for which this type of observations is available so far. The observed H$\\alpha$ emission is spatially unresolved, indicating that the size of the H$\\alpha$ emitting region is smaller than ~ 0.21 and 0.12 au for HD 179218 and HD 141529 (~ 15 and 16 R*, respectively). This is smaller than for the two other HAeBes previously observed with the same instrumentation. Two different scenarios have been explored in order to explain the compact line emitting regions. A hot, several thousand K, blackbody disc is consistent with the observations of HD 179218 and HD 141569. Magnetospheric accretion (MA) is able to reproduce the bulk of the H$\\alpha$ emission shown by HD 179218, confirming previous estimates from MA shock modelling with a mass accretion rate of 10^-8 Msun/yr, and an inclination to the line of sight between 30 and 50 degr. The H$\\al...

  11. The Molecular Gas Environment around Two Herbig Ae/Be Stars: Resolving the Outflows of LkHα 198 and LkHα 225S

    Science.gov (United States)

    Matthews, Brenda C.; Graham, James R.; Perrin, Marshall D.; Kalas, Paul

    2007-12-01

    Observations of outflows associated with pre-main-sequence stars reveal details about morphology, binarity, and evolutionary states of young stellar objects. We present molecular line data from the Berkeley-Illinois-Maryland Association array and Five Colleges Radio Astronomical Observatory toward the regions containing the Herbig Ae/Be stars LkHα 198 and LkHα 225S. Single-dish observations of 12CO J=1-0, 13CO J=1-0, N2H+ J=1-0, and CS J=2-1 were made over a field of 4.3'×4.3' for each species. 12CO J=1-0 data from FCRAO were combined with high-resolution BIMA array data to achieve a naturally weighted synthesized beam of 6.75''×5.5'' toward LkHα 198 and 5.7''×3.95'' toward LkHα 225S, representing resolution improvements of factors of approximately 10 and 5 over existing data. By using uniform weighting, we achieved another factor of 2 improvement. The outflow around LkHα 198 resolves into at least four outflows, none of which are centered on LkHα 198-IR, but even at our resolution we cannot exclude the possibility of an outflow associated with this source. In the LkHα 225S region we find evidence for two outflows associated with LkHα 225S itself, and a third outflow is likely driven by this source. Identification of the driving sources is still resolution limited and is also complicated by the presence of three clouds along the line of sight toward the Cygnus molecular cloud. 13CO J=1-0 is present in the environments of both stars along with cold, dense gas as traced by CS J=2-1 and (in LkHα 225S) N2H+ J=1-0. No 2.6 mm continuum is detected in either region in relatively shallow maps compared to existing continuum observations.

  12. H2CO and N2H+ in Protoplanetary Disks: Evidence for a CO-ice Regulated Chemistry

    CERN Document Server

    Qi, Chunhua; Wilner, David

    2013-01-01

    We present Submillimeter Array observations of H2CO and N2H+ emission in the disks around the T Tauri star TW Hya and the Herbig Ae star HD 163296 at 2"-6" resolution and discuss the distribution of these species with respect to CO freeze-out. The H2CO and N2H+ emission toward HD 163296 does not peak at the continuum emission center that marks the stellar position but is instead significantly offset. Using a previously developed model for the physical structure of this disk, we show that the H2CO observations are reproduced if H2CO is present predominantly in the cold outer disk regions. A model where H2CO is present only beyond the CO snow line (estimated at a radius of 160 AU) matches the observations well. We also show that the average H2CO excitation temperature, calculated from two transitions of H2CO observed in these two disks and a larger sample of disks around T Tauri stars in the DISCS (the Disk Imaging Survey of Chemistry with SMA) program, is consistent with the CO freeze-out temperature of 20 K. ...

  13. ALMA imaging of the CO snowline of the HD 163296 disk with DCO

    NARCIS (Netherlands)

    Mathews, G. S.; Klaassen, P. D.; Juhasz, A.; Harsono, D.; Chapillon, E.; van Dishoeck, E. F.; Espada, D.; de Gregorio-Monsalvo, I.; Hales, A.; Hogerheijde, M. R.; Mottram, J. C.; Rawlings, M. G.; Takahashi, S.; Testi, L.

    2013-01-01

    Context. The high spatial resolution and line sensitivity of the Atacama Large Millimeter/submillimeter Array (ALMA) opens the possibility of resolving emission from molecules in large samples of circumstellar disks. With an understanding of the conditions under which these molecules can have high a

  14. PDS 144: The First Confirmed Herbig Ae - Herbig Ae Wide Binary

    CERN Document Server

    Hornbeck, J B; Perrin, M D; Wisniewski, J P; Tofflemire, B M; Brown, A; Holtzman, J A; Arraki, K; Hamaguchi, K; Woodgate, B; Petre, R; Daly, B; Grogin, N A; Bonfield, D G; Williger, G M; Lauroesch, J T; 10.1088/0004-637X/744/1/54

    2012-01-01

    PDS 144 is a pair of Herbig Ae stars that are separated by 5.35" on the sky. It has previously been shown to have an A2Ve Herbig Ae star viewed at 83\\circ inclination as its northern member and an A5Ve Herbig Ae star as its southern member. Direct imagery revealed a disk occulting PDS 144 N - the first edge-on disk observed around a Herbig Ae star. The lack of an obvious disk in direct imagery suggested PDS 144 S might be viewed face-on or not physically associated with PDS 144 N. Multi-epoch Hubble Space Telescope imagery of PDS 144 with a 5 year baseline demonstrates PDS 144 N & S are comoving and have a common proper motion with TYC 6782-878-1. TYC 6782-878-1 has previously been identified as a member of Upper Sco sub-association A at d = 145 \\pm 2 pc with an age of 5-10 Myr. Ground-based imagery reveals jets and a string of Herbig-Haro knots extending 13' (possibly further) which are aligned to within 7\\circ \\pm 6\\circ on the sky. By combining proper motion data and the absence of a dark mid-plane wit...

  15. A gas density drop in the inner 6 AU of the transition disk around the Herbig Ae star HD 139614: Further evidence for a giant planet inside the disk?

    CERN Document Server

    Carmona, A; Kamp, I; Baruteau, C; Matter, A; Ancker, M van den; Pinte, C; Kóspál, A; Audard, M; Liebhart, A; Sicilia-Aguilar, A; Pinilla, P; Regály, Zs; Güdel, M; Henning, Th; Cieza, L A; Baldovin-Saavedra, C; Meeus, G; Eiroa, C

    2016-01-01

    Context: Quantifying the gas content inside the dust gaps of transition disks is important to establish their origin. Aims: We seek to constrain the surface density of warm gas in the disk of HD 139614, a Herbig Ae star with a transition disk exhibiting a dust gap from 2.3 to 6 AU. Methods: We have obtained ESO/VLT CRIRES high-resolution spectra of CO ro-vibrational emission. We derive disk structure constraints by modeling the line profiles, the spectroastrometric signal, and the rotational diagrams using flat Keplerian disk models. Results: We detected v=1-0 12CO, 2-1 12CO, 1-0 13CO, 1-0 C18O, and 1-0 C17O ro-vibrational lines. 12CO v=1-0 lines have an average width of 14 km/s, Tgas of 450 K and an emitting region from 1 to 15 AU. 13CO and C18O lines are on average 70 and 100 K colder, 1 and 4 km/s narrower, and are dominated by emission at R>6 AU. The 12CO v=1-0 line profile indicates that if there is a gap in the gas it must be narrower than 2 AU. We find that a drop in the gas surface density (delta_gas)...

  16. Hardware Implementation of AES

    Directory of Open Access Journals (Sweden)

    Aakrati Chaturvedi

    2014-01-01

    Full Text Available The Advanced Encryption Standard algorithm can be efficiently programmed in software and implemented in hardware. Field Programmable Gate Array (FPGA devices are considered as efficient and cost effective solution for hardware. This research is in context to efficient hardware implementation of AES algorithm with language platform as VHDL (Very High Speed Integrated Circuit Hardware Description language. This research is in context to efficient hardware implementation of AES algorithm with 128-192-256 key all in one module with language platform as VHDL (Very High Speed Integrated Circuit Hardware Description language. The software part has been created, processed and simulated through Xilinx ISE 9.2. A compact design approach has been chosen to implement the algorithm with minimal hardware. As for hardware, Spartan 3AN family device (XC3S700A device is used

  17. AE3D

    Energy Technology Data Exchange (ETDEWEB)

    2016-06-20

    AE3D solves for the shear Alfven eigenmodes and eigenfrequencies in a torodal magnetic fusion confinement device. The configuration can be either 2D (e.g. tokamak, reversed field pinch) or 3D (e.g. stellarator, helical reversed field pinch, tokamak with ripple). The equations solved are based on a reduced MHD model and sound wave coupling effects are not currently included.

  18. Sensitive survey for 13CO, CN, H2CO, and SO in the disks of T Tauri and Herbig Ae stars II: Stars in $\\rho$ Oph and upper Scorpius

    CERN Document Server

    Reboussin, L; Simon, M; Grosso, N; Wakelam, V; Di Folco, E; Dutrey, A; Piétu, V

    2015-01-01

    We attempt to determine the molecular composition of disks around young low-mass stars in the $\\rho$ Oph region and to compare our results with a similar study performed in the Taurus-Auriga region. We used the IRAM 30 m telescope to perform a sensitive search for CN N=2-1 in 29 T Tauri stars located in the $\\rho$ Oph and upper Scorpius regions. $^{13}$CO J=2-1 is observed simultaneously to provide an indication of the level of confusion with the surrounding molecular cloud. The bandpass also contains two transitions of ortho-H$_2$CO, one of SO, and the C$^{17}$O J=2-1 line, which provides complementary information on the nature of the emission. Contamination by molecular cloud in $^{13}$CO and even C$^{17}$O is ubiquitous. The CN detection rate appears to be lower than for the Taurus region, with only four sources being detected (three are attributable to disks). H$_2$CO emission is found more frequently, but appears in general to be due to the surrounding cloud. The weaker emission than in Taurus may sugges...

  19. AES i ARM procesori

    Directory of Open Access Journals (Sweden)

    Danijela D. Protić

    2013-12-01

    Full Text Available Potreba za zaštitom informacija dovodi do velikih problema u izradi prenosivih uređaja kojima su limitirani snaga, memorija i energija. Ukoliko se takvim uređajima dodaju koprocesori, koji treba da obavljaju funkcije kriptozaštite, njihove se dimenzije povećavaju, pojavljuje se nefleksibilnost pa cena uređaja raste i do nekoliko puta. Na drugoj strani, algoritmi za zaštitu podataka su često memorijski zahtevni, a zbog velikog broja operacija koje je potrebno izvršavati u procesima šifrovanja i dešifrovanja, koprocesori često uspore rad osnovnog procesora. Za jedan od standarda za kriptozaštitu, AES, NIST je prihvatio Rijndaelov blokovski algoritam sa dužinom ulaznog i izlaznog bloka od 128 b, i dužinama šifarskog ključa od 128 b, 192 b i 256 b. Zbog karakteristika male potrošnje, 32-bitske arhitekture i brzog izvršavanja instrukcija, ARM procesori mogu da realizuju kriptozaštitu podataka, između ostalog i AES-om, a da ne opterete glavne procese u sistemima u kojima se koriste. Tehnologija ARM-a zaštićena je kao intelektualna svojina, pa je veliki broj proizvođača koristi za razvoj sopstvenih proizvoda, što je rezultovalo činjenicom da je u svetu proizvedeno preko 2 milijarde čipova koji su bazirani na ovoj tehnologiji. U radu su prikazane mogućnosti za poboljšanja u izvršenju algoritma AES primenom najnovijih verzija ARM procesora.

  20. PDS 144: The First Confirmed Herbig Ae-Herbig Ae Wide Binary

    Science.gov (United States)

    Hornbeck, J. B.; Grady, C. A.; Perrin, M. D.; Wisniewski, J. P.; Tofflemire, B. M.; Brown, A.; Holtzman, J. A.; Arraki, K.; Hamaguchi, K.; Woodgate, B.; Petre, R.; Daly, B.; Grogin, N. A.; Bonfield, D. G.; Williger, G. M.; Lauroesch, J. T.

    2012-01-01

    PDS 144 is a pair of Herbig Ae stars that are separated by 5farcs35 on the sky. It has previously been shown to have an A2Ve Herbig Ae star viewed at 83° inclination as its northern member and an A5Ve Herbig Ae star as its southern member. Direct imagery revealed a disk occulting PDS 144 N—the first edge-on disk observed around a Herbig Ae star. The lack of an obvious disk in direct imagery suggested PDS 144 S might be viewed face-on or not physically associated with PDS 144 N. Multi-epoch Hubble Space Telescope imagery of PDS 144 with a 5 year baseline demonstrates PDS 144 N & S are comoving and have a common proper motion with TYC 6782-878-1. TYC 6782-878-1 has previously been identified as a member of Upper Sco sub-association A at d = 145 ± 2 pc with an age of 5-10 Myr. Ground-based imagery reveals jets and a string of Herbig-Haro knots extending 13' (possibly further) which are aligned to within 7° ± 6° on the sky. By combining proper motion data and the absence of a dark mid-plane with radial velocity data, we measure the inclination of PDS 144 S to be i = 73° ± 7°. The radial velocity of the jets from PDS 144 N & S indicates they, and therefore their disks, are misaligned by 25° ± 9°. This degree of misalignment is similar to that seen in T Tauri wide binaries.

  1. A gas density drop in the inner 6 AU of the transition disk around the Herbig Ae star HD 139614 . Further evidence for a giant planet inside the disk?

    Science.gov (United States)

    Carmona, A.; Thi, W. F.; Kamp, I.; Baruteau, C.; Matter, A.; van den Ancker, M.; Pinte, C.; Kóspál, A.; Audard, M.; Liebhart, A.; Sicilia-Aguilar, A.; Pinilla, P.; Regály, Zs.; Güdel, M.; Henning, Th.; Cieza, L. A.; Baldovin-Saavedra, C.; Meeus, G.; Eiroa, C.

    2017-02-01

    Context. Quantifying the gas surface density inside the dust cavities and gaps of transition disks is important to establish their origin. Aims: We seek to constrain the surface density of warm gas in the inner disk of HD 139614, an accreting 9 Myr Herbig Ae star with a (pre-)transition disk exhibiting a dust gap from 2.3 ± 0.1 to 5.3 ± 0.3 AU. Methods: We observed HD 139614 with ESO/VLT CRIRES and obtained high-resolution (R 90 000) spectra of CO ro-vibrational emission at 4.7 μm. We derived constraints on the disk's structure by modeling the CO isotopolog line-profiles, the spectroastrometric signal, and the rotational diagrams using grids of flat Keplerian disk models. Results: We detected υ = 1 → 0 12CO, 2→1 12CO, 1→0 13CO, 1→0 C18O, and 1→0 C17O ro-vibrational lines. Lines are consistent with disk emission and thermal excitation. 12CO υ = 1 → 0 lines have an average width of 14 km s-1, Tgas of 450 K and an emitting region from 1 to 15 AU. 13CO and C18O lines are on average 70 and 100 K colder, 1 and 4 km s-1 narrower than 12CO υ = 1 → 0, and are dominated by emission at R ≥ 6 AU. The 12CO υ = 1 → 0 composite line-profile indicates that if there is a gap devoid of gas it must have a width narrower than 2 AU. We find that a drop in the gas surface density (δgas) at R R R R ≤ 1 AU of 5 × 1015 cm-2 (NH ≤ 5 × 1019 cm-2). Conclusions: The dust gap in the disk of HD 139614 has molecular gas. The distribution and amount of gas at R ≤ 6 AU in HD 139614 is very different from that of a primordial disk. The gas surface density in the disk at R ≤ 1 AU and at 1 R 2 AU) gas gap, suggest the presence of an embedded program 091.C-0671(B).

  2. References: AePW publications

    Data.gov (United States)

    National Aeronautics and Space Administration — This page is the repository for the publications resulting from the AePW. This includes the special sessions at conferences: AIAA ASM 2012, Grapevine TX; AIAA SDM...

  3. AE Recorder Characteristics and Development.

    Energy Technology Data Exchange (ETDEWEB)

    Partridge, Michael E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Curtis, Shane Keawe [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); McGrogan, David Paul [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-11-01

    The Anomalous Environment Recorder (AE Recorder) provides a robust data recording capability for multiple high-shock applications including earth penetrators. The AE Recorder, packaged as a 2.4" di ameter cylinder 3" tall, acquires 12 accelerometer, 2 auxiliary, and 6 discrete signal channels at 250k samples / second. Recording depth is 213 seconds plus 75ms of pre-trigger data. The mechanical, electrical, and firmware are described as well as support electro nics designed for the first use of the recorder.

  4. An ALMA Survey of DCN/H13CN and DCO+/H13CO+ in Protoplanetary Disks

    Science.gov (United States)

    Huang, Jane; Öberg, Karin I.; Qi, Chunhua; Aikawa, Yuri; Andrews, Sean M.; Furuya, Kenji; Guzmán, Viviana V.; Loomis, Ryan A.; van Dishoeck, Ewine F.; Wilner, David J.

    2017-02-01

    The deuterium enrichment of molecules is sensitive to their formation environment. Constraining patterns of deuterium chemistry in protoplanetary disks is therefore useful for probing how material is inherited or reprocessed throughout the stages of star and planet formation. We present ALMA observations at ∼0.″6 resolution of DCO+, H13CO+, DCN, and H13CN in the full disks around T Tauri stars AS 209 and IM Lup, in the transition disks around T Tauri stars V4046 Sgr and LkCa 15, and in the full disks around Herbig Ae stars MWC 480 and HD 163296. We also present ALMA observations of HCN in the IM Lup disk. DCN, DCO+, and H13CO+ are detected in all disks, and H13CN in all but the IM Lup disk. We find efficient deuterium fractionation for the sample, with estimates of disk-averaged DCO+/HCO+ and DCN/HCN abundance ratios ranging from ∼0.02–0.06 and ∼0.005–0.08, respectively, which is comparable to values reported for other interstellar environments. The relative distributions of DCN and DCO+ vary between disks, suggesting that multiple formation pathways may be needed to explain the diverse emission morphologies. In addition, gaps and rings observed in both H13CO+ and DCO+ emission provide new evidence that DCO+ bears a complex relationship with the location of the midplane CO snowline.

  5. Optical spectrophotometry of oscillations and flickering in AE Aquarii

    Science.gov (United States)

    Welsh, William F.; Horne, Keith; Oke, J. B.

    1993-01-01

    We observed rapid variations in the nova-like cataclysmic variable AE Aquarii for 1.7 hr with 4.3 s time resolution using the 30-channel (3227-10494 A) spectrophotometer on the Hale 5 m telescope. The 16.5 and 33.0 s oscillations show a featureless blue spectrum that can be represented by a blackbody with temperature and area much smaller than the accretion disk. Models consisting of the sum of a K star spectrum and a hydrogen slab in LTE at T = 6000-10,000 K can fit the spectrum of AE Aquarii reasonably well. The spectrum of a flare indicates optically thin gas with T = 8000-12,000 K. The energy released by the flare is large compared to typical stellar flares.

  6. Evolution from protoplanetary to debris discs: The transition disc around HD 166191

    CERN Document Server

    Kennedy, G M; Lisse, C M; Ménard, F; Sitko, M L; Wyatt, M C; Bayliss, D D R; DeMeo, F E; Crawford, K B; Kim, D L; Rudy, R J; Russell, R W; Sibthorpe, B; Skinner, M A; Zhou, G

    2013-01-01

    HD 166191 has been identified by several studies as hosting a rare and extremely bright warm debris disc with an additional outer cool disc component. However, an alternative interpretation is that the star hosts a disc that is currently in transition between a full gas disc and a largely gas-free debris disc. With the help of new optical to mid-IR spectra and Herschel imaging, we argue that the latter interpretation is supported in several ways: i) we show that HD 166191 is co-moving with the ~4 Myr-old Herbig Ae star HD 163296, suggesting that the two have the same age, ii) the disc spectrum of HD 166191 is well matched by a standard radiative transfer model of a gaseous protoplanetary disc with an inner hole, and iii) the HD 166191 mid-IR silicate feature is more consistent with similarly primordial objects. We note some potential issues with the debris disc interpretation that should be considered for such extreme objects, whose lifetime at the current brightness is mush shorter than the stellar age, or i...

  7. The Herbig Ae SB2 System HD 104237

    CERN Document Server

    Cowley, Charles R; Hubrig, Swetlana

    2013-01-01

    The double-lined spectroscopic binary HD 104237 (DX Cha) is part of a complex system of some half-dozen nearby young stars. We report a significant change from an orbit for the SB2 system derived from 1999-2000 observations. We obtain abundances from the primary and secondary spectra. The abundance analysis uses both detailed spectral synthesis and determinations based on equivalent widths of weak absorption lines with W(lambda) typically < 25 mA. Abundances are derived for 25 elements in the primary, and 17 elements in the secondary. Apart from lithium and zirconium, abundances do not depart significantly from solar. Lithium may be marginally enhanced with respect to the meteoritic value in the primary. It somewhat depleted in the secondary. The emission-line spectrum is typical of Herbig Ae stars. We compare and contrast the spectra of the HD 104237 primary and two other Herbig Ae stars with low v.sin(i), HD 101412 and HD 190073.

  8. Biclique cryptanalysis of the full AES

    DEFF Research Database (Denmark)

    Bogdanov, Andrey; Khovratovich, Dmitry; Rechberger, Christian

    2011-01-01

    Since Rijndael was chosen as the Advanced Encryption Standard (AES), improving upon 7-round attacks on the 128-bit key variant (out of 10 rounds) or upon 8-round attacks on the 192/256-bit key variants (out of 12/14 rounds) has been one of the most difficult challenges in the cryptanalysis of block...... ciphers for more than a decade. In this paper, we present the novel technique of block cipher cryptanalysis with bicliques, which leads to the following results: The first key recovery method for the full AES-128 with computational complexity 2126.1. The first key recovery method for the full AES-192...... with computational complexity 2189.7. The first key recovery method for the full AES-256 with computational complexity 2254.4. Key recovery methods with lower complexity for the reduced-round versions of AES not considered before, including cryptanalysis of 8-round AES-128 with complexity 2124.9. Preimage search...

  9. Chromosome isolation by flow sorting in Aegilops umbellulata and Ae. comosa and their allotetraploid hybrids Ae. biuncialis and Ae. geniculata.

    Directory of Open Access Journals (Sweden)

    István Molnár

    Full Text Available This study evaluates the potential of flow cytometry for chromosome sorting in two wild diploid wheats Aegilops umbellulata and Ae. comosa and their natural allotetraploid hybrids Ae. biuncialis and Ae. geniculata. Flow karyotypes obtained after the analysis of DAPI-stained chromosomes were characterized and content of chromosome peaks was determined. Peaks of chromosome 1U could be discriminated in flow karyotypes of Ae. umbellulata and Ae. biuncialis and the chromosome could be sorted with purities exceeding 95%. The remaining chromosomes formed composite peaks and could be sorted in groups of two to four. Twenty four wheat SSR markers were tested for their position on chromosomes of Ae. umbellulata and Ae. comosa using PCR on DNA amplified from flow-sorted chromosomes and genomic DNA of wheat-Ae. geniculata addition lines, respectively. Six SSR markers were located on particular Aegilops chromosomes using sorted chromosomes, thus confirming the usefulness of this approach for physical mapping. The SSR markers are suitable for marker assisted selection of wheat-Aegilops introgression lines. The results obtained in this work provide new opportunities for dissecting genomes of wild relatives of wheat with the aim to assist in alien gene transfer and discovery of novel genes for wheat improvement.

  10. The far-infrared behaviour of Herbig Ae/Be discs: Herschel PACS photometry

    CERN Document Server

    Pascual, N; Meeus, G; Marshall, J P; Mendigutía, I; Sandell, G

    2016-01-01

    Herbig Ae/Be objects are pre-main sequence stars surrounded by gas- and dust-rich circumstellar discs. These objects are in the throes of star and planet formation, and their characterisation informs us of the processes and outcomes of planet formation processes around intermediate mass stars. Here we analyse the spectral energy distributions of disc host stars observed by the Herschel Open Time Key Programme `Gas in Protoplanetary Systems'. We present Herschel/PACS far-infrared imaging observations of 22 Herbig Ae/Bes and 5 debris discs, combined with ancillary photometry spanning ultraviolet to sub-millimetre wavelengths. From these measurements we determine the diagnostics of disc evolution, along with the total excess, in three regimes spanning near-, mid-, and far-infrared wavelengths. Using appropriate statistical tests, these diagnostics are examined for correlations. We find that the far-infrared flux, where the disc becomes optically thin, is correlated with the millimetre flux, which provides a meas...

  11. Radiation thermo-chemical models of protoplanetary discs. IV. Modelling CO ro-vibrational emission from Herbig Ae discs

    NARCIS (Netherlands)

    Thi, W. F.; Kamp, I.; Woitke, P.; van der Plas, G.; Bertelsen, R.; Wiesenfeld, L.

    2013-01-01

    Context. The carbon monoxide (CO) ro-vibrational emission from discs around Herbig Ae stars and T Tauri stars with strong ultraviolet emissions suggests that fluorescence pumping from the ground X1Σ+ to the electronic A1Π state of CO should be taken into account in disc models. Aims: We wish to unde

  12. Radiation thermo-chemical models of protoplanetary discs IV. Modelling CO ro-vibrational emission from Herbig Ae discs

    NARCIS (Netherlands)

    Thi, W. F.; Kamp, I.; Woitke, P.; van der Plas, G.; Bertelsen, R.; Wiesenfeld, L.

    2013-01-01

    Context. The carbon monoxide (CO) ro-vibrational emission from discs around Herbig Ae stars and T Tauri stars with strong ultraviolet emissions suggests that fluorescence pumping from the ground X-1 Sigma(+) to the electronic A(1)Pi state of CO should be taken into account in disc models. Aims. We w

  13. AE Aquarii represents a new subclass of Cataclysmic Variables

    CERN Document Server

    Ikhsanov, N R

    2012-01-01

    We analyze properties of the unique nova-like star AE Aquarii identified with a close binary system containing a red dwarf and a very fast rotating magnetized white dwarf. It cannot be assigned to any of the three commonly adopted sub-classes of Cataclysmic Variables: Polars, Intermediate Polars, and Accreting non-magnetized White Dwarfs. Our study has shown that the white dwarf in AE Aqr is in the ejector state and its dipole magnetic moment is $\\mu ~ 1.5 \\times 10^{34} G cm^3$. It switched into this state due to intensive mass exchange between the system components during a previous epoch. A high rate of disk accretion onto the white dwarf surface resulted in temporary screening of its magnetic field and spin-up of the white dwarf to its present spin period. Transition of the white dwarf to the ejector state had occurred at a final stage of the spin-up epoch as its magnetic field emerged from the accreted plasma due to diffusion. In the frame of this scenario AE Aqr represents a missing link in the chain of...

  14. Probing the 2D temperature structure of protoplanetary disks with Herschel observations of high-J CO lines

    CERN Document Server

    Fedele, D; Kama, M; Bruderer, S; Hogerheijde, M

    2016-01-01

    The gas temperature structure of protoplanetary disks is a key ingredient for interpreting various disk observations and for quantifying the subsequent evolution of these systems. The comparison of low- and mid-$J$ CO rotational lines is a powerful tool to assess the temperature gradient in the warm molecular layer of disks. Spectrally resolved high-$J$ ($J_{\\rm u} > 14$) CO lines probe intermediate distances and heights from the star that are not sampled by (sub-)millimeter CO spectroscopy. This paper presents new {\\it Herschel}/HIFI and archival PACS observations of $^{12}$CO, $^{13}$CO and \\cii \\ emission in 4 Herbig AeBe (HD 100546, HD 97048, IRS 48, HD 163296) and 3 T Tauri (AS 205, S CrA, TW Hya) disks. In the case of the T Tauri systems AS 205 and S CrA, the CO emission has a single-peaked profile, likely due to a slow wind. For all other systems, the {\\it Herschel} CO spectra are consistent with pure disk emission and the spectrally-resolved lines (HIFI) and the CO rotational ladder (PACS) are analyze...

  15. Dynamic AES – Extending the Lifetime?

    DEFF Research Database (Denmark)

    Tange, Henrik; Andersen, Birger

    2014-01-01

    proven that AES is vulnerable to side-channelattacks, related sub-key attacks and biclicque attacks. This paper introducesa new dynamic version of AES where the main flow is depending on theTNAF (τ -adic Non-Adjacent Form) value. This new approach can preventside-channel attacks, related sub-key attacks...

  16. Waveform Analysis of AE in Composites

    Science.gov (United States)

    Prosser, William H.

    1998-01-01

    Advanced, waveform based acoustic emission (AE) techniques have been developed to evaluate damage mechanisms in the testing of composite materials. This approach, more recently referred to as Modal AE, provides an enhanced capability to discriminate and eliminate noise signals from those generated by damage mechanisms. Much more precise source location can also be obtained in comparison to conventional, threshold crossing arrival time determination techniques. Two successful examples of the application of Modal AE are presented in this work. In the first, the initiation of transverse matrix cracking in cross-ply, tensile coupons was monitored. In these tests, it was documented that the same source mechanism, matrix cracking, can produce widely different AE signal amplitudes dependent on laminate stacking sequence and thickness. These results, taken together with well known propagation effects of attenuation and dispersion of AE signals in composite laminates, cast further doubt on the validity of simple amplitude or amplitude distribution analysis for AE source determination. For the second example, delamination propagation in composite ring specimens was monitored. Pressurization of these composite rings is used to simulate the stresses in a composite rocket motor case. AE signals from delamination propagation were characterized by large amplitude flexural plate mode components which have long signal durations because of the large dispersion of this mode.

  17. New related-key rectangle attacks on reduced AES-192 and AES-256

    Institute of Scientific and Technical Information of China (English)

    WEI YongZhuang; HU YuPu

    2009-01-01

    In this paper, we examine the security of reduced AES-192 and AES-256 against related-key rectangle attacks by exploiting the weakness in the AES key schedule. We find the following two new attacks: 9-round reduced AES-192 with 4 related keys, and 10-round reduced AES-256 with 4 related keys. Our results show that related-key rectangle attack with 4 related keys on 9-round reduced AES-192 requires a data complexity of about 2101 chosen plaintexts and a time complexity of about 2174.8 encryptions, and moreover, related-key rectangle attack with 4 related keys on 10-round reduced AES-256 requires a data complexity of about 297.5 chosen plaintexts and a time complexity of about 2254 encryptions. These attacks are the first known attacks on 9-round reduced AES-192 and 10-round reduced AES-256 with only 4 related keys. Furthermore, we give an improvement of the 10-round reduced AES-192 attack presented at FSE2007, which reduces both the data complexity and the time complexity.

  18. Calculating Auroral Oval Pattern by AE Index

    Institute of Scientific and Technical Information of China (English)

    CHEN Anqin; LI Jiawei; YANG Guanglin; WANG Jingsong

    2008-01-01

    The relationship between the auroral oval pattern, i.e., location, size, shape, and intensity, and the auroral electrojet activity index (AE index) is studied. It is found that the maximal auroral intensity is elliptically distributed, and the lengths of semimajor and semiminor axes are positively correlated to AE.The intensity along the normal of the auroral oval can be satisfyingly described by a Gaussian distribution,and the maximum and the full width at half maximum of the Gaussian distribution are both positively correlated to AE. Based on these statistical results, a series of experimental formulas as a function of AE are developed to calculate the location, size, shape, and intensity of the auroral oval. These formulas are validated by the auroral images released by SWPC/NOAA.

  19. Masking a Compact AES S-box

    Science.gov (United States)

    2007-08-07

    Lecture Notes in Computer Science , pages 309–18, 2001. [2] D. Canright. A very compact S-box for AES. In CHES2005, volume 3659 of Lecture Notes in Computer Science , pages...et al., editor, CHES2003, volume 2779 of Lecture Notes in Computer Science , pages 319–333. Springer, 2003. [4] Jovan Dj. Golić and Christophe Tymen...Multiplicative masking and power analysis of AES. In CHES 2002, volume 2523 of Lecture

  20. 15 CFR 758.2 - Automated Export System (AES).

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 2 2010-01-01 2010-01-01 false Automated Export System (AES). 758.2... CLEARANCE REQUIREMENTS § 758.2 Automated Export System (AES). The Census Bureau's Foreign Trade Statistics...) electronically using the Automated Export System (AES). In order to use AES, you must apply directly to...

  1. Attacks and countermeasures on AES and ECC

    DEFF Research Database (Denmark)

    Tange, Henrik; Andersen, Birger

    2013-01-01

    is foreseeable while the rounds are performed. ECC (Elliptic Curve Cryptography) is used as a public key crypto system with the key purpose of creating a private shared between two participants in a communication network. Attacks on ECC include the Pohlig-Hellman attack and the Pollard's rho attack. Furthermore......AES (Advanced Encryption Standard) is widely used in LTE and Wi-Fi communication systems. AES has recently been exposed to new attacks which have questioned the overall security of AES. The newest attack is a so called biclique attack, which is using the fact that the content of the state array...... side-channels attacks can be applied to ECC. This paper reflects an ongoing research in the field of countermeasures against the attacks mentioned above....

  2. [Modern spectral estimation of ICP-AES].

    Science.gov (United States)

    Zhang, Z; Jia, Q; Liu, S; Guo, L; Chen, H; Zeng, X

    2000-06-01

    The inductively coupled plasma atomic emission spectrometry (ICP-AES) and its signal characteristics were discussed using modern spectral estimation technique. The power spectra density (PSD) was calculated using the auto-regression (AR) model of modern spectra estimation. The Levinson-Durbin recursion method was used to estimate the model parameters which were used for the PSD computation. The results obtained with actual ICP-AES spectra and measurements showed that the spectral estimation technique was helpful for the better understanding about spectral composition and signal characteristics.

  3. AES ALGORITHM IMPLEMENTATION IN PROGRAMMING LANGUAGES

    Directory of Open Access Journals (Sweden)

    Luminiţa DEFTA

    2010-12-01

    Full Text Available Information encryption represents the usage of an algorithm to convert an unknown message into an encrypted one. It is used to protect the data against unauthorized access. Protected data can be stored on a media device or can be transmitted through the network. In this paper we describe a concrete implementation of the AES algorithm in the Java programming language (available from Java Development Kit 6 libraries and C (using the OpenSSL library. AES (Advanced Encryption Standard is an asymmetric key encryption algorithm formally adopted by the U.S. government and was elected after a long process of standardization.

  4. Atomic-AES: A compact implementation of the AES encryption/decryption core

    DEFF Research Database (Denmark)

    Banik, Subhadeep; Bogdanov, Andrey; Regazzoni, Francesco

    2016-01-01

    D that require access to both the AES encryption and decryption modules. In this paper we look to investigate whether the basic circuit of Moradi et al. can be tweaked to provide dual functionality of encryption and decryption (ENC/DEC) while keeping the hardware overhead as low as possible. As a result, we...... report an 8-bit serialized AES circuit that provides the functionality of both encryption and decryption and occupies around 2645 GE with a latency of 226 cycles. This is a substantial improvement over the next smallest AES ENC/DEC circuit (Grain of Sand) by Feldhofer et al. which takes around 3400 gates...

  5. AE8/AP8 Implementations in AE9/AP9, IRBEM, and SPENVIS

    Science.gov (United States)

    2014-02-18

    period applies to orbit generation only; AE8/AP8 utilizes geomagnetic field models from other epochs as specified in the table below.) SHIELDOSE2 model...Cain, J. C., S. J. Hendricks, R. A. Langel, and W. V. Hudson (1967), A proposed model for the international geomagnetic reference field, 1965, J...trapped particle fluxes with the NASA models AP-8 and AE-8, Radiat. Meas., 26, pp. 947-952. International Association of Geomagnetism and Aeronomy

  6. AES Water Architecture Study Interim Results

    Science.gov (United States)

    Sarguisingh, Miriam J.

    2012-01-01

    The mission of the Advanced Exploration System (AES) Water Recovery Project (WRP) is to develop advanced water recovery systems in order to enable NASA human exploration missions beyond low earth orbit (LEO). The primary objective of the AES WRP is to develop water recovery technologies critical to near term missions beyond LEO. The secondary objective is to continue to advance mid-readiness level technologies to support future NASA missions. An effort is being undertaken to establish the architecture for the AES Water Recovery System (WRS) that meets both near and long term objectives. The resultant architecture will be used to guide future technical planning, establish a baseline development roadmap for technology infusion, and establish baseline assumptions for integrated ground and on-orbit environmental control and life support systems (ECLSS) definition. This study is being performed in three phases. Phase I of this study established the scope of the study through definition of the mission requirements and constraints, as well as indentifying all possible WRS configurations that meet the mission requirements. Phase II of this study focused on the near term space exploration objectives by establishing an ISS-derived reference schematic for long-duration (>180 day) in-space habitation. Phase III will focus on the long term space exploration objectives, trading the viable WRS configurations identified in Phase I to identify the ideal exploration WRS. The results of Phases I and II are discussed in this paper.

  7. 22 CFR 120.30 - The Automated Export System (AES).

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false The Automated Export System (AES). 120.30... DEFINITIONS § 120.30 The Automated Export System (AES). The Automated Export System (AES) is the Department of... system for collection of export data for the Department of State. In accordance with this subchapter...

  8. Search for gamma-ray emission from AE Aquarii with seven years of FERMI-LAT observations

    CERN Document Server

    Li, Jian; Rea, Nanda; Wilhelmi, Emma de Ona; Papitto, Alessandro; Hou, Xian; Mauche, Christopher W

    2016-01-01

    AE Aquarii (AE Aqr) is a cataclysmic binary hosting one of the fastest rotating (P$_{\\rm spin}$ = 33.08 s) white dwarfs known. Based on seven years of Fermi Large Area Telescope (LAT) Pass 8 data, we report on a deep search for gamma-ray emission from AE Aqr. Using X-ray observations from ASCA, XMM-Newton, Chandra, Swift, Suzaku, and NuSTAR, spanning 20 years, we substantially extend and improve the spin ephemeris of AE Aqr. Using this ephemeris, we searched for gamma-ray pulsations at the spin period of the white dwarf. No gamma-ray pulsations were detected above 3 $\\sigma$ significance. Neither phase-averaged gamma-ray emission nor gamma-ray variability of AE Aquarii is detected by Fermi-LAT. We impose the most restrictive upper limit to the gamma-ray flux from AE Aqr to date: $1.3\\times 10^{-12}$ erg cm$^{-2}$ s$^{-1}$ in the 100 MeV-300 GeV energy range, providing constraints on models.

  9. A new processing method for the AE index

    Institute of Scientific and Technical Information of China (English)

    ZHANG LingQian; LIU ZhenXing; MA ZhiWei; W. BAUMJOHANN; WU Jian; M. DUNLOP; SHI JianKui; LU Li; WANG JiYe

    2008-01-01

    In this paper, we introduce an effective processing method to acquire the time de-rivative of the AE index as e coefficient. Using this coefficient, the AE index can be divided into the four stages: quiet, ascending, descending and active stages. The statistical results show that the ascending and descending stages of the AE index are dominant and occupy two thirds of the whole period. An analysis of the rela-tionship between the occurrence frequencies of the Dst index end AE index in solar cycle 23 shows that the monthly variation of the occurrence frequencies of the ascending stage of AE is closely related to the decrease of the Dst index.

  10. A new processing method for the AE index

    Institute of Scientific and Technical Information of China (English)

    W.; BAUMJOHANN; M.; DUNLOP

    2008-01-01

    In this paper, we introduce an effective processing method to acquire the time de-rivative of the AE index as a coefficient. Using this coefficient, the AE index can be divided into the four stages: quiet, ascending, descending and active stages. The statistical results show that the ascending and descending stages of the AE index are dominant and occupy two thirds of the whole period. An analysis of the rela-tionship between the occurrence frequencies of the Dst index and AE index in solar cycle 23 shows that the monthly variation of the occurrence frequencies of the ascending stage of AE is closely related to the decrease of the Dst index.

  11. Chaotic appearance of the AE index

    Science.gov (United States)

    Shan, L.-H.; Hansen, P.; Goertz, C. K.; Smith, R. A.

    1991-01-01

    Results are reported from a stochastic analysis of a 5-day time series of the geomagnetic AE index during an active period. The original data, the power spectrum, and the autocorrelation function are shown, and the steps in the analysis are described in detail. It is found that the autocorrelation time scale is about 50 min, giving a correlation dimension (for the construction of a time series of m-dimensional vectors) of 2.4. This result is consistent with either colored-noise or deterministic-chaos magnetosphere models, indicating the need for further investigation.

  12. Simulation and Experimental Investigation on the AE Tomography to Improve AE Source Location in the Concrete Structure

    Directory of Open Access Journals (Sweden)

    Yu Jiang

    2014-01-01

    Full Text Available Acoustic emission (AE tomography, which is based on the time-travel tomography with AE events as its signal sources, is a new visualization tool for inspecting and locating the internal damages in the structures. In this paper, AE tomography is applied to examine a man-made damage in a typical heterogeneous concrete structure to validate its effectiveness. Firstly, the finite element (ABAQUS/Explicit simulation model of the concrete structure with one damaged circle in its center is built, and the simulated AE signals are obtained to establish the AE tomography. The results show that the damaged circle in the created model can be visualized clearly with the AE tomography in its original location. Secondly, the concrete specimen based on the FE model is fabricated, and the pencil lead break (PLB signal is taken as the exciting source for AE tomography. It is shown that the experimental results have good consistency with the FE simulation results, which also verifies the feasibility of the finite element model for AE tomography. Finally, the damage source location based on AE tomography is compared with the traditional time of arrival (TOA location method, and the better location accuracy is obtained with the AE tomography. The research results indicate that AE tomography has great potential in the application of structure damage detection.

  13. 撞瘪的AE86

    Institute of Scientific and Technical Information of China (English)

    王非

    2009-01-01

    你有爱AE86的朋友?我信你有,谁都有。问问他们,AE86出演过什么电影?他们会先笑你,然后告诉你:当然是"头文字D"。是啊,他们当然是想跟你聊藤原拓海。忘了给你这样答案的朋友,跟他们自己想的不一样,他们一点都不酷。看起来,他们丝毫未经过1980-90以前的indie movie潮流洗礼。他们知道Vincent Gallo是谁吗?或者Jim Jarmusch,或者Lars von Trier,或者Gus Van Sant?就连这些基本项,他们都未必知道(Sean Penn出演Gus Van Sant的Milk,今年都有Oscar the best actor可拿,早已征服主流),遑论更小众更独立的电影人。

  14. ASASSN-14ae: A Tidal Disruption Event at 200 Mpc

    CERN Document Server

    Holoien, Thomas W -S; Bersier, D; Kochanek, C S; Stanek, K Z; Shappee, B J; Grupe, D; Basu, U; Beacom, J F; Brimacombe, J; Brown, J S; Davis, A B; Jencson, J; Pojmanski, G; Szczygiel, D M

    2014-01-01

    ASASSN-14ae is a candidate tidal disruption event (TDE) found at the center of SDSS J110840.11+340552.2 ($d\\simeq200$ Mpc) by the All-Sky Automated Survey for Supernovae (ASAS-SN), a global array of 14-cm telescopes. The host galaxy is an early type spiral with no signs of an active galactic nucleus (AGN) and with little recent star formation. We present follow-up photometric and spectroscopic observations of the source, including optical data from ground-based telescopes and ultraviolet and optical data from Swift. From blackbody fits to the host-subtracted spectral energy distribution, we find that the transient had a peak luminosity of $L\\simeq8\\times10^{43}$ erg s$^{-1}$ and a total integrated energy of $E\\simeq1.5\\times10^{50}$ ergs over the $\\sim3$ months of observations presented. The blackbody temperature of the transient remains roughly constant at $T\\sim20,000$ K while the luminosity declines by nearly 1.5 orders of magnitude during this time, a drop that is most consistent with an exponential, $L\\p...

  15. Morphologies of protostellar outflows: An ALMA view

    CERN Document Server

    Peters, Thomas; Seifried, Daniel; Banerjee, Robi; Klessen, Ralf S

    2014-01-01

    The formation of stars is usually accompanied by the launching of protostellar outflows. Observations with the Atacama Large Millimetre/sub-millimetre Array (ALMA) will soon revolutionalise our understanding of the morphologies and kinematics of these objects. In this paper, we present synthetic ALMA observations of protostellar outflows based on numerical magnetohydrodynamic collapse simulations. We find significant velocity gradients in our outflow models and a very prominent helical structure within the outflows. We speculate that the disk wind found in the ALMA Science Verification Data of HD 163296 presents a first instance of such an observation.

  16. BOREAS AES Campbell Scientific Surface Meteorological Data

    Science.gov (United States)

    Atkinson, G. Barrie; Funk, Barrie; Knapp. David E. (Editor); Hall, Forrest G. (Editor)

    2000-01-01

    Canadian AES personnel collected data related to surface and atmospheric meteorological conditions over the BOREAS region. This data set contains 15-minute meteorological data from 14 automated meteorology stations located across the BOREAS region. Included in this data are parameters of date, time, mean sea level pressure, station pressure, temperature, dew point, wind speed, resultant wind speed, resultant wind direction, peak wind, precipitation, maximum temperature in the last hour, minimum temperature in the last hour, pressure tendency, liquid precipitation in the last hour, relative humidity, precipitation from a weighing gauge, and snow depth. Temporally, the data cover the period of August 1993 to December 1996. The data are provided in tabular ASCII files, and are classified as AFM-Staff data.

  17. Acoustic Emissions (AE) Electrical Systems' Health Monitoring Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Acoustic Emissions (AE) are associated with physical events, such as thermal activity, dielectric breakdown, discharge inception, as well as crack nucleation and...

  18. Multiple Lookup Table-Based AES Encryption Algorithm Implementation

    Science.gov (United States)

    Gong, Jin; Liu, Wenyi; Zhang, Huixin

    Anew AES (Advanced Encryption Standard) encryption algorithm implementation was proposed in this paper. It is based on five lookup tables, which are generated from S-box(the substitution table in AES). The obvious advantages are reducing the code-size, improving the implementation efficiency, and helping new learners to understand the AES encryption algorithm and GF(28) multiplication which are necessary to correctly implement AES[1]. This method can be applied on processors with word length 32 or above, FPGA and others. And correspondingly we can implement it by VHDL, Verilog, VB and other languages.

  19. 山羊草Aegilops kotschyi及其供体种Ae.longissima和Ae.umbellulata的醇溶蛋白研究%Gliadin Variations in Aegilops kotschyi and its Progentiors Ae. longissima and Ae. umbellulata

    Institute of Scientific and Technical Information of China (English)

    李霞; 郑有良; 刘登才; 颜泽洪

    2003-01-01

    采用酸性聚丙烯酰胺凝胶电泳(APAGE)法对11份Aegilops kotschyi及其S1染色体组供体种Ae.longissima2份和U染色体组供体种Ae.umbellulata6份进行了醇溶蛋白位点的研究.结果表明:11份Ae.kotschyi共分离出32条带,31条具有多态性,占96.88%,每份材料可以分离出10~17条谱带,其中仅1条(3.12%)是共有带;11份Ae.kotschyi的遗传距离的变异范围在0~0.704之间,平均为0.409;11份Ae.kotschyi分离出的多数醇溶蛋白谱带均与其染色体组供体种Ae.longissi-ma及Ae.umbellulata相同,但仍有8条谱带未在两供体种中找到;11份Ae.kotschyi的醇溶蛋白多态性(96.88%)明显高于Ae.longissima(52.94%)与Ae.umbellulata(88.89%);11份Ae.kotschyi中有4份表现出了一定的特征带,分析知可能在γ区发生了较大的变异.

  20. The global compendium of Aedes aegypti and Ae. albopictus occurrence

    Science.gov (United States)

    Kraemer, Moritz U. G.; Sinka, Marianne E.; Duda, Kirsten A.; Mylne, Adrian; Shearer, Freya M.; Brady, Oliver J.; Messina, Jane P.; Barker, Christopher M.; Moore, Chester G.; Carvalho, Roberta G.; Coelho, Giovanini E.; van Bortel, Wim; Hendrickx, Guy; Schaffner, Francis; Wint, G. R. William; Elyazar, Iqbal R. F.; Teng, Hwa-Jen; Hay, Simon I.

    2015-07-01

    Aedes aegypti and Ae. albopictus are the main vectors transmitting dengue and chikungunya viruses. Despite being pathogens of global public health importance, knowledge of their vectors’ global distribution remains patchy and sparse. A global geographic database of known occurrences of Ae. aegypti and Ae. albopictus between 1960 and 2014 was compiled. Herein we present the database, which comprises occurrence data linked to point or polygon locations, derived from peer-reviewed literature and unpublished studies including national entomological surveys and expert networks. We describe all data collection processes, as well as geo-positioning methods, database management and quality-control procedures. This is the first comprehensive global database of Ae. aegypti and Ae. albopictus occurrence, consisting of 19,930 and 22,137 geo-positioned occurrence records respectively. Both datasets can be used for a variety of mapping and spatial analyses of the vectors and, by inference, the diseases they transmit.

  1. Some aspects of AE application in tool condition monitoring

    Science.gov (United States)

    Jemielniak

    2000-03-01

    Acoustic emission (AE) is rather a well-known form of non-destructive testing. In the last few years the technology of the AE measurement has been expanded to cover the area of tool condition monitoring. The paper presents some experience of Warsaw University of Technology (WUT) in such applications of AE. It provides an interpretation of common AE signal distortions and possible solutions to avoid them. Furthermore, a characteristic study of several different AE and ultrasonic sensors being used in WUT is furnished. Evaluation of the applicability of some basic measures of acoustic emission for tool condition monitoring is also presented in the paper. Finally paper presents a method of the catastrophic tool failure detection in turning, which uses symptoms other than the direct magnitude AERMS signal. The method is based on the statistical analysis of the distributions of the AERMS signal.

  2. Chemical abundance analysis of symbiotic giants. RW Hya, SY Mus, BX Mon, and AE Ara

    CERN Document Server

    Galan, Cezary; Hinkle, Kenneth H; Schmidt, Miroslaw R; Gromadzki, Mariusz

    2014-01-01

    Symbiotic stars are the long period, binary systems of strongly interacting stars at the final stages of evolution which can be useful tool to understand the chemical evolution of the Galaxy and the formation of stellar populations. Knowledge of the chemical composition of the symbiotic giants is essential to advancing our understanding of these issues but unfortunately reliably determinations exist only in a few cases. We perform a program for detailed chemical composition analysis in over 30 symbiotic giants, based on the high resolution, near-IR spectra, obtained with Phoenix/Gemini South spectrometer. The methods of the standard LTE analysis is used to obtain photospheric abundances of CNO and elements around iron peak. Here we present results obtained for four objects: RW Hya, SY Mus, BX Mon, and AE Ara. Our analysis revealed a significantly sub-solar metallicity (Me/H ~ -0.75) for RW Hya, a slightly sub-solar metallicities (Me/H ~ 0.2-0.3) in BX Mon and AE Ara, and a near-solar metallicity in SY Mus. 12...

  3. Roche tomography of cataclysmic variables - VII. The long-term magnetic activity of AE Aqr

    CERN Document Server

    Hill, C A; Steeghs, D; Dhillon, V S; Shahbaz, T

    2016-01-01

    We present a long-term study of the secondary star in the cataclysmic variable AE~Aqr, using Roche tomography to indirectly image starspots on the stellar surface spanning 8~years of observations. The 7 maps show an abundance of spot features at both high and low latitudes. We find that all maps have at least one large high-latitude spot region, and we discuss its complex evolution between maps, as well as its compatibility with current dynamo theories. Furthermore, we see the apparent growth in fractional spot coverage, $f_{\\mathrm{s}}$, around $45^{\\circ}$~latitude over the duration of observations, with a persistently high $f_{\\mathrm{s}}$ near latitudes of $20^{\\circ}$. These bands of spots may form as part of a magnetic activity cycle, with magnetic flux tubes emerging at different latitudes, similar to the `butterfly' diagram for the Sun. We discuss the nature of flux tube emergence in close binaries, as well as the activity of AE~Aqr in the context of other stars.

  4. Roche tomography of cataclysmic variables - VI. Differential rotation of AE Aqr - Not tidally locked!

    CERN Document Server

    Hill, Colin; Shahbaz, Tariq; Steeghs, Danny; Dhillon, Vik

    2014-01-01

    We present Roche tomograms of the K4V secondary star in the cataclysmic variable AE Aqr, reconstructed from two datasets taken 9 days apart, and measure the differential rotation of the stellar surface. The tomograms show many large, cool starspots, including a large high-latitude spot and a prominent appendage down the trailing hemisphere. We find two distinct bands of spots around 22$^{\\circ}$ and 43$^{\\circ}$ latitude, and estimate a spot coverage of 15.4-17% on the northern hemisphere. Assuming a solar-like differential rotation law, the differential rotation of AE Aqr was measured using two different techniques. The first method yields an equator-pole lap time of 269 d and the second yields a lap time of 262 d. This shows the star is not fully tidally locked, as was previously assumed for CVs, but has a co-rotation latitude of $\\sim 40^{\\circ}$. We discuss the implications that these observations have on stellar dynamo theory, as well as the impact that spot traversal across the first Lagrangian point ma...

  5. Gene flow between wheat and wild relatives: empirical evidence from Aegilops geniculata, Ae. neglecta and Ae. triuncialis.

    Science.gov (United States)

    Arrigo, Nils; Guadagnuolo, Roberto; Lappe, Sylvain; Pasche, Sophie; Parisod, Christian; Felber, François

    2011-09-01

    Gene flow between domesticated species and their wild relatives is receiving growing attention. This study addressed introgression between wheat and natural populations of its wild relatives (Aegilops species). The sampling included 472 individuals, collected from 32 Mediterranean populations of three widespread Aegilops species (Aegilops geniculata, Ae. neglecta and Ae. triuncialis) and compared wheat field borders to areas isolated from agriculture. Individuals were characterized with amplified fragment length polymorphism fingerprinting, analysed through two computational approaches (i.e. Bayesian estimations of admixture and fuzzy clustering), and sequences marking wheat-specific insertions of transposable elements. With this combined approach, we detected substantial gene flow between wheat and Aegilops species. Specifically, Ae. neglecta and Ae. triuncialis showed significantly more admixed individuals close to wheat fields than in locations isolated from agriculture. In contrast, little evidence of gene flow was found in Ae. geniculata. Our results indicated that reproductive barriers have been regularly bypassed during the long history of sympatry between wheat and Aegilops.

  6. Reconfigurable Secure Video Codec Based on DWT and AES Processor

    Directory of Open Access Journals (Sweden)

    Rached Tourki

    2010-01-01

    Full Text Available In this paper, we proposed a secure video codec based on the discrete wavelet transformation (DWT and the Advanced Encryption Standard (AES processor. Either, use of video coding with DWT or encryption using AES is well known. However, linking these two designs to achieve secure video coding is leading. The contributions of our work are as follows. First, a new method for image and video compression is proposed. This codec is a synthesis of JPEG and JPEG2000,which is implemented using Huffman coding to the JPEG and DWT to the JPEG2000. Furthermore, an improved motion estimation algorithm is proposed. Second, the encryptiondecryption effects are achieved by the AES processor. AES is aim to encrypt group of LL bands. The prominent feature of this method is an encryption of LL bands by AES-128 (128-bit keys, or AES-192 (192-bit keys, or AES-256 (256-bit keys.Third, we focus on a method that implements partial encryption of LL bands. Our approach provides considerable levels of security (key size, partial encryption, mode encryption, and has very limited adverse impact on the compression efficiency. The proposed codec can provide up to 9 cipher schemes within a reasonable software cost. Latency, correlation, PSNR and compression rate results are analyzed and shown.

  7. TRANSITIONAL DISKS AROUND YOUNG LOW MASS STARS

    Directory of Open Access Journals (Sweden)

    P. D'Alessio

    2009-01-01

    have been interpreted as produced by disks with inner holes, which have been classi ed as \\Transitional Disks". These disks are considered the evolutionary link between the full disks typically found around the young T Tauri and Herbig Ae stars, and the debris disks, found around some main sequence stars. In this contribution we summarize the observed/inferred characteristics of these transitional disks and also some of the models proposed to explain their peculiar geometry.

  8. Novel Frequency Hopping Sequences Generator Based on AES Algorithm

    Institute of Scientific and Technical Information of China (English)

    李振荣; 庄奕琪; 张博; 张超

    2010-01-01

    A novel frequency hopping(FH) sequences generator based on advanced encryption standard(AES) iterated block cipher is proposed for FH communication systems.The analysis shows that the FH sequences based on AES algorithm have good performance in uniformity, correlation, complexity and security.A high-speed, low-power and low-cost ASIC of FH sequences generator is implemented by optimizing the structure of S-Box and MixColumns of AES algorithm, proposing a hierarchical power management strategy, and applying ...

  9. Validation and empirical correction of MODIS AOTand AE over ocean

    Directory of Open Access Journals (Sweden)

    N. A. J. Schutgens

    2013-04-01

    Full Text Available We present a validation study of Coll. 5 MODIS level 2 Aqua and Terra AOT and AE over ocean by comparison to coastal and island AERONET sites for the years 2003–2009. We show that MODIS AOT exhibits significant biases due to windspeed and cloudiness of the observed scene, while MODIS AE although overall unbiased, exhibits less spatial contrast on global scales than the AERONET observations. The same behaviour can be seen when MODIS AOT is compared against marine AERONET data, suggesting that the spatial coverage of our datasets does not preclude global conclusions. Thus, we develop empirical correction formulae for MODIS AOT and AE that signifcantly improve agreement of MODIS and AERONET observations. We show these correction formulae to be robust. Finally, we study random errors in the corrected MODIS AOT and AE and show that they mainly depend on AOT itself, although small contributions are present due to windspeed and cloud-fraction in AOT random errors and due to Ångström exponent and cloud fraction in AE random errors. Our analysis yields significantly higher random AOT errors than the official MODIS error estimate (0.03 + 0.05 τ, while random AE errors are smaller than might be expected. We interpret these findings in reference to the MODIS retrieval algorithm. This new dataset of bias-corrected MODIS AOT and AE over ocean is intended for aerosol model validation and assimilation studies, but also has consequences as a stand-alone observational product. For instance, the corrected dataset suggests that much less fine mode aerosol is transported across the Pacific and Atlantic oceans.

  10. A scaling relationship between AE and natural earthquakes

    Science.gov (United States)

    Yoshimitsu, N.; Kawakata, H.; Takahashi, N.

    2013-12-01

    Micro fracture which occurs during rock fracture experiments are called acoustic emission (AE), and it help us to understand detailed processes of fault growth. However, it was unclear whether AE can be considered as a small earthquake or not. Usually, the seismic moment and the corner frequency are used for characterizing source property. It has been reported that the seismic moment is inversely proportional to the cube of corner frequency for natural earthquakes (with magnitude higher than ~ -4). In this study, we examine continuity of this relationship toward smaller magnitude of AE (around magnitude -8), estimating the source parameters of AE. Previously, it was impossible to record AE waveforms by broadband transducers under tri-axial conditions due to lack of pressure seal mechanism. Here we achieved protection of broadband transducers to use them under high pressure environments. This achievement enabled us to do spectral analysis of AE. At the same time, we also achieved multi-channel continuous recording with a high sampling rate, so as not to miss some events smaller than threshold or hide some events behind the mask times by triggered recording. We prepared a cylindrical Westerly granite sample, 50 mm in diameter and 100 mm in height. Sealed nine broadband transducers (sensitive range; 100 kHz - 2000 kHz) were attached on the sample surface. High sampling recording as 20 MS/s per channel was continued, during tri-axial loading (confining pressure: 10 MPa) which was continued to be controlled even after the peak strength. More than 6000 hypocenters were estimated from all pick data during the experiment. We clustered events around the peak strength, so that their differences of hypocenter locations were shorter than 2 mm and their cross correlation values for more than four channels were higher than 0.8. Then, we analyzed two of the largest clusters. After calibrating transducer response, we obtained displacement spectra for S waves, and estimated their

  11. The Peculiar Binary System AE Aquarii from its Characteristic Multi-wavelength Emission

    Directory of Open Access Journals (Sweden)

    Oruru B.

    2014-01-01

    Full Text Available The multi-wavelength properties of the novalike variable system AE Aquarii are discussed in terms of the interaction between the accretion inflow from a late-type main sequence star and the magnetosphere of a fast rotating white dwarf. This results in an efficient magnetospheric propeller process and particle acceleration. The spin-down of the white dwarf at a period rate of 5.64×10−14 s s−1 results in a huge spin-down luminosity of Ls−d ≃ 6 10×33 erg s−1. Hence, the observed non-thermal hard X-ray emission and VHE and TeV gamma-ray emission may suggest that AE Aquarii can be placed in the category of spin-powered pulsars. Besides, observed hard X-ray luminosity of LX,hard ≤ 5 × 1030 erg s−1 constitutes 0.1 % of the total spin-down luminosity of the white dwarf. This paper will discuss some recent theoretical studies and data analysis of the system.

  12. Shaft Crack Identification Based on Vibration and AE Signals

    Directory of Open Access Journals (Sweden)

    Wenxiu Lu

    2011-01-01

    Full Text Available The shaft crack is one of the main serious malfunctions that often occur in rotating machinery. However, it is difficult to locate the crack and determine the depth of the crack. In this paper, the acoustic emission (AE signal and vibration response are used to diagnose the crack. The wavelet transform is applied to AE signal to decompose into a series of time-domain signals, each of which covers a specific octave frequency band. Then an improved union method based on threshold and cross-correlation method is applied to detect the location of the shaft crack. The finite element method is used to build the model of the cracked rotor, and the crack depth is identified by comparing the vibration response of experiment and simulation. The experimental results show that the AE signal is effective and convenient to locate the shaft crack, and the vibration signal is feasible to determine the depth of shaft crack.

  13. A model with nonzero rise time for AE signals

    Indian Academy of Sciences (India)

    M A Majeed; C R L Murthy

    2001-10-01

    Acoustic emission (AE) signals are conventionally modelled as damped or decaying sinusoidal functions. A major drawback of this model is its negligible or zero rise time. This paper proposes an alternative model, which provides for the rising part of the signal without sacrificing the analytical tractability and simplicity of the conventional model. Signals obtained from the proposed model through computer programs are illustrated for demonstrating their parity with actual AE signals. Analytic expressions for the time-domain parameters, viz., peak amplitude and rise time used in conventional AE signal analysis, are also derived. The model is believed to be also of use in modelling the output signal of any transducer that has finite rise time and fall time.

  14. Meteosat Images Encryption based on AES and RSA Algorithms

    Directory of Open Access Journals (Sweden)

    Boukhatem Mohammed Belkaid

    2015-06-01

    Full Text Available Satellite image Security is playing a vital role in the field of communication system and Internet. This work is interested in securing transmission of Meteosat images on the Internet, in public or local networks. To enhance the security of Meteosat transmission in network communication, a hybrid encryption algorithm based on Advanced Encryption Standard (AES and Rivest Shamir Adleman (RSA algorithms is proposed. AES algorithm is used for data transmission because of its higher efficiency in block encryption and RSA algorithm is used for the encryption of the key of the AES because of its management advantages in key cipher. Our encryption system generates a unique password every new session of encryption. Cryptanalysis and various experiments have been carried out and the results were reported in this paper, which demonstrate the feasibility and flexibility of the proposed scheme.

  15. Numerical and experimental characterizations of low frequency MEMS AE sensors

    Science.gov (United States)

    Saboonchi, Hossain; Ozevin, Didem

    2013-04-01

    In this paper, new MEMS Acoustic Emission (AE) sensors are introduced. The transduction principle of the sensors is capacitance due to gap change. The sensors are numerically modeled using COMSOL Multiphysics software in order to estimate the resonant frequencies and capacitance values, and manufactured using MetalMUMPS process. The process includes thick metal layer (20 μm) made of nickel for freely vibration layer and polysilicon layer as the stationary layer. The metal layer provides a relatively heavy mass so that the spring constant can be designed high for low frequency sensor designs in order to increase the collapse voltage level (proportional to the stiffness), which increases the sensor sensitivity. An insulator layer is deposited between stationary layer and freely vibration layer, which significantly reduces the potential of stiction as a failure mode. As conventional AE sensors made of piezoelectric materials cannot be designed for low frequencies (vacuum packaging. The MEMS sensor responses are compared with similar frequency piezoelectric AE sensors.

  16. AM/AE/AA三元共聚物的合成%Synthesis of AM/AE/AA tercopolymer

    Institute of Scientific and Technical Information of China (English)

    李艳华; 杨军; 吴晓艺

    2000-01-01

    以烷基酚聚氧乙烯醚合成了丙烯酸酯活性大单体(AE);以水为溶剂,过硫酸成了AM/AE/AA(丙烯酸酯/活性大单体/丙烯酸)的共聚物表面活性剂并讨论了反应条件对共聚,物表面活性剂性质的影响。结果表明,合成的AM/AE/AA共聚物具有较高的表面活性.%A surface-active macromonomer of poly(oxylethylene alkylphenyl ether)acrylate was prepared with poly(oxylethylene alkylphenyl ether)and acrylic acid.A copolymer surfactant(AM/AE/AA)of poly(oxylethylene alkylpheny ether)acrylate(AE),acrylamide(AM)and acrylic acid(AA)was synthesized using K2S2O8 as initiation and water as solution.The effects of reaction conditions on the properties of surfactant was discussed.It was found that the copolymer of AM/AE/AA exhibited higher surface activity.

  17. Security of the AES with a Secret S-Box

    DEFF Research Database (Denmark)

    Tiessen, Tyge; Knudsen, Lars Ramkilde; Kölbl, Stefan;

    2015-01-01

    How does the security of the AES change when the S-box is replaced by a secret S-box, about which the adversary has no knowledge? Would it be safe to reduce the number of encryption rounds? In this paper, we demonstrate attacks based on integral cryptanalysis which allow to recover both the secret...... key and the secret S-box for respectively four, five, and six rounds of the AES. Despite the significantly larger amount of secret information which an adversary needs to recover, the attacks are very efficient with time/data complexities of 217/216, 238/240 and 290/264, respectively. Another...

  18. Practical Attacks on AES-like Cryptographic Hash Functions

    DEFF Research Database (Denmark)

    Kölbl, Stefan; Rechberger, Christian

    2015-01-01

    Despite the great interest in rebound attacks on AES-like hash functions since 2009, we report on a rather generic, albeit keyschedule-dependent, algorithmic improvement: A new message modification technique to extend the inbound phase, which even for large internal states makes it possible to dr...

  19. Ultra-low power S-Boxes architecture for AES

    Institute of Scientific and Technical Information of China (English)

    XING Ji-peng; ZOU Xue-cheng; GUO Xu

    2008-01-01

    It is crucial to design energy-efficient advancedcncryption standard (AES) cryptography for low power embeddedsystems powered by limited battery. Since the S-Boxes consumemuch of the total AES circuit power, an efficient approach toreducing the AES power consumption consists in reducing theS-Boxes power consumption. Among various implementationsof S-Boxes, the most energy-efficient one is the decoder-switch-encoder (DSE) architecture. In this paper, we refine the DSEarchitecture and propose one faster, more compact S-Boxesarchitecture of lower power: an improved and full-balanced DSEarchitecture. This architecture achieves low power consumptionof 68 μW at 10 MHz using 0.25 μm 1.8V UMC CMOStechnology. Compared with the original DSE S-Boxes, it furtherreduces the delay, gate count and power consumption by 8%,14% and 10% respectively. At the sane time, simulation resultsshow that the improved DSE S-Boxes has the best performanceamong various S-Boxes architectures in terms of power-areaproduct and power-delay product, and it is optimal forimplementing low power AES cryptography.

  20. The applicability of Aes commercial and naval ships

    Energy Technology Data Exchange (ETDEWEB)

    Nienhuis, U. [Netheerlands Institute for Maritime Research (Netherlands); Dingemanse, R.P. [Imtech Marine and Industry (Netherlands); Van Vugt, J. [TNO-Bouw/CMC (Netherlands); Cock, J. de [HMA Power Systems (Netherlands); Boonstra, H. [Delf Univ. of Technology (Netherlands); Van der Ploeg, B. [Royal Netherlands Navy (Netherlands)

    2000-07-01

    The paper presents the main findings of the recently completed Dutch national study on All Electric Ships. The study aimed to identify and quantify the pros and cons of AES for commercial and naval ships. In the course of the study a general model, called GES, was developed to assess the (financial) consequences of AES. The model allows for the definition of arbitrary power plant concepts, irrespective of their nature. An estimate of future developments was included to gauge the evolution of the cost-benefit balance of AES. With the help of this model, a number of ships were investigated relative to their suitability for AFS. The paper presents the employed evaluation tool in some detail. Further the main findings for some of the ships are presented. The general applicability of the all-electric concept for ships is dealt with, and the most promising candidates are singled out. The authors also review the main development work remaining for AES to take off for a wide range of ships. (authors)

  1. The Herbig Ae SB2 system HD 104237

    Directory of Open Access Journals (Sweden)

    Cowley C. R.

    2014-01-01

    Full Text Available We present here the most recent abundance analysis of this Herbig Ae system based on high-resolution UVES and HARPS spectra and the results of our magnetic field measurements using high-resolution spectra obtained with HARPSpol.

  2. Near-Earth bursty bulk flows and AE index

    Institute of Scientific and Technical Information of China (English)

    ZHANG LingQian; SHI JianKui; LIU ZhenXing; W BAUMJOHANN; MA ZhiWei; M. W. DUNLOP; C. CARR; H. REME

    2008-01-01

    With the 4-s resolution data of the magnetometer and the ion plasma analyzer on TC-1 from June to November of each year during the period of 2004-2006, we statistically analyzed the occurrence rate of both convective and field-aligned bursty flows (FABFs). A near-Earth bursty bulk flow (NEBBF) occurred during both the quiet time and substorm process. In general, the magnetic field and the plasma density began oscillating with the appearance of the NEBBF associated with a distinct increase of the AE index. The increase of AE index during the NEBBF was more than 100 nT in both quiet time and substorm process. The statistical analysis indicated that the occurrence rates of the FABFs were nearly the same in the dif-ferent stages of the AE index, but the occurrence rate of the NEBBFs was much higher in the growth stage of the AE index, indicating that the NEBBFs were di-rectly related to the growth and expansion phases of the substorm. The observa-tions suggested that the quite large number of BBFs from the mid magnetotail could enter into the near-Earth tail and play important role in triggering the sub-storm onset.

  3. Enhanced ATM Security using Biometric Authentication and Wavelet Based AES

    Directory of Open Access Journals (Sweden)

    Sreedharan Ajish

    2016-01-01

    Full Text Available The traditional ATM terminal customer recognition systems rely only on bank cards, passwords and such identity verification methods are not perfect and functions are too single. Biometrics-based authentication offers several advantages over other authentication methods, there has been a significant surge in the use of biometrics for user authentication in recent years. This paper presents a highly secured ATM banking system using biometric authentication and wavelet based Advanced Encryption Standard (AES algorithm. Two levels of security are provided in this proposed design. Firstly we consider the security level at the client side by providing biometric authentication scheme along with a password of 4-digit long. Biometric authentication is achieved by considering the fingerprint image of the client. Secondly we ensure a secured communication link between the client machine to the bank server using an optimized energy efficient and wavelet based AES processor. The fingerprint image is the data for encryption process and 4-digit long password is the symmetric key for the encryption process. The performance of ATM machine depends on ultra-high-speed encryption, very low power consumption, and algorithmic integrity. To get a low power consuming and ultra-high speed encryption at the ATM machine, an optimized and wavelet based AES algorithm is proposed. In this system biometric and cryptography techniques are used together for personal identity authentication to improve the security level. The design of the wavelet based AES processor is simulated and the design of the energy efficient AES processor is simulated in Quartus-II software. Simulation results ensure its proper functionality. A comparison among other research works proves its superiority.

  4. Star Clusters

    OpenAIRE

    Gieles, M.

    1993-01-01

    Star clusters are observed in almost every galaxy. In this thesis we address several fundamental problems concerning the formation, evolution and disruption of star clusters. From observations of (young) star clusters in the interacting galaxy M51, we found that clusters are formed in complexes of stars and star clusters. These complexes share similar properties with giant molecular clouds, from which they are formed. Many (70%) of the young clusters will not survive the fist 10 Myr, due to t...

  5. Stars and Star Myths.

    Science.gov (United States)

    Eason, Oliver

    Myths and tales from around the world about constellations and facts about stars in the constellations are presented. Most of the stories are from Greek and Roman mythology; however, a few Chinese, Japanese, Polynesian, Arabian, Jewish, and American Indian tales are also included. Following an introduction, myths are presented for the following 32…

  6. The AES/EBU Digital Audio Transmission Standard%AES/EBU数字音频传输标准

    Institute of Scientific and Technical Information of China (English)

    侯书婷; 杨宇; 徐品

    2014-01-01

    In order to ensure that all kinds of digital audio equipment in the studio to be connected to each other and transmitting data securely,the AES/ EBU ( audio engineering association/European broadcast-ing union) formulated the AES/ EBU digital audio interface standard and revised it in 1992. The standard has become a popular professional digital audio standard. This paper mainly introduces the standard in de-tail.%为了保证演播室中各种数字音频设备之间能够相互连接并且安全的传输数据,AES/EBU(声频工程协会/欧洲广播联盟)制定了AES/EBU数字音频接口标准并于1992对它进行重新修订。该标准现已成为专业数字音频较为流行的标准。本文主要对该标准进行详细的介绍。

  7. Differential inhibition of AE1 and AE2 anion exchangers by oxonol dyes and by novel polyaminosterol analogs of the shark antibiotic squalamine.

    Science.gov (United States)

    Alper, S L; Chernova, M N; Williams, J; Zasloff, M; Law, F Y; Knauf, P A

    1998-01-01

    Oxonol and polyaminosterol drugs were examined as inhibitors of recombinant mouse AE1 and AE2 anion exchangers expressed in Xenopus laevis oocytes and were compared as inhibitors of AE1-mediated anion flux in red cells and in HL-60 cells that express AE2. The oxonols WW-781, diBA(5)C4, and diBA(3)C4 inhibited HL-60 cell Cl-/Cl- exchange with IC50 values from 1 to 7 microM, 100-1000 times less potent than their IC50 values for red cell Cl-/anion exchange. In Xenopus oocytes, diBA(5)C4 inhibited AE1-mediated Cl- efflux several hundred times more potently than that mediated by AE2. Several novel squalamine-related polyaminosterols were also evaluated as anion exchange inhibitors. In contrast to diBA(5)C4, polyaminosterol 1361 inhibited oocyte-expressed AE2 8-fold more potently than AE1 (IC50 0.6 versus 5.2 microM). The 3-fold less potent desulfo-analog, 1360, showed similar preference for AE2. It was found that 1361 also partially inhibited Cl- efflux from red cells, whereas neither polyaminosterol inhibited Cl efflux from HL60 cells. Thus, the oxonol diBA(5)C4 is >100-fold more potent as an inhibitor of AE1 than of AE2, whereas the polyaminosterols 1360 and 1361 are 8-fold more potent as inhibitors of AE2 than of AE1. Assay conditions and cell type influenced IC50 values for both classes of compounds.

  8. Two Methods of AES Implementation Based on CPLD/FPGA

    Institute of Scientific and Technical Information of China (English)

    刘常澍; 彭艮鹏; 王晓卓

    2004-01-01

    This paper describes two single-chip--complex programmable logic devices/field programmable gate arrays(CPLD/FPGA)--implementations of the new advanced encryption standard (AES) algorithm based on the basic iteration architecture (design [A]) and the hybrid pipelining architecture (design [B]). Design [A] is an encryption-and-decryption implementation based on the basic iteration architecture. This design not only supports 128-bit, 192-bit, 256-bit keys, but saves hardware resources because of the iteration architecture and sharing technology. Design [B] is a method of the 2×2 hybrid pipelining architecture. Based on the AES interleaved mode of operation, the design successfully accomplishes the algorithm, which operates in the feedback mode (cipher block chaining). It not only guarantees security of encryption/decryption, but obtains high data throughput of 1.05 Gb/s. The two designs have been realized on Aitera's EP20k300EBC652-1 devices.

  9. The research of DPA attacks against AES implementations

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This article examines vulnerabilities to power analysis attacks between software and hardware implementations of cryptographic algorithms. Representative platforms including an Atmel 89S8252 8-bit processor and a 0.25 μm 1.8 v standard cell circuit are proposed to implement the advance encryption standard (AES). A simulation-based experimental environment is built to acquire power data, and single-bit differential power analysis (DPA), and multi-bit DPA and correlation power analysis (CPA) attacks are conducted on two implementations respectively. The experimental results show that the hardware implementation has less data-dependent power leakages to resist power attacks. Furthermore, an improved DPA approach is proposed. It adopts hamming distance of intermediate results as power model and arranges plaintext inputs to differentiate power traces to the maximal probability. Compared with the original power attacks, our improved DPA performs a successful attack on AES hardware implementations with acceptable power measurements and fewer computations.

  10. Accelerating Solution Proposal of AES Using a Graphic Processor

    Directory of Open Access Journals (Sweden)

    STRATULAT, M.

    2011-11-01

    Full Text Available The main goal of this work is to analyze the possibility of using a graphic processing unit in non graphical calculations. Graphic Processing Units are being used nowadays not only for game engines and movie encoding/decoding, but also for a vast area of applications, like Cryptography. We used the graphic processing unit as a cryptographic coprocessor in order accelerate AES algorithm. Our implementation of AES is on a GPU using CUDA architecture. The performances obtained show that the CUDA implementation can offer speedups of 11.95Gbps. The tests are conducted in two directions: running the tests on small data sizes that are located in memory and large data that are stored in files on hard drives.

  11. AES Encryption and Decryption Using Direct3D 10 API

    Directory of Open Access Journals (Sweden)

    Adrian Marius Chiuta

    2011-06-01

    Full Text Available Current video cards (GPUs – Graphics Processing Units are very programmable, have become much more powerful than the CPUs and they are very affordable. In this paper, we present an implementation for the AES algorithm using Direct3D 10 certified GPUs. The graphics API Direct3D 10 is the first version that allows the use of integer operations, making from the traditional GPUs (that works only with floating point numbers, General Purpose GPUs that can be used for a large number of algorithms, including encryption. We present the performance of the symmetric key encryption algorithm – AES, on a middle range GPU and on a middle range quad core CPU. On the testing system, the developed solution is almost 3 times faster on the GPU than on one single core CPU, showing that the GPU can perform as an efficient cryptographic accelerator.

  12. On the origin of the peculiar cataclysmic variable AE Aquarii

    CERN Document Server

    Beskrovnaya, N G

    2014-01-01

    The nova-like variable AE Aquarii is a close binary system containing a red dwarf and a magnetized white dwarf rotating with the period of 33 seconds. A short spin period of the white dwarf is caused by an intensive mass exchange between the system components during a previous epoch. We show that a high rate of disk accretion onto the white dwarf surface resulted in temporary screening of its magnetic field and spin-up of the white dwarf to its present spin period. Transition of the white dwarf to the ejector state occurred at a final stage of the spin-up epoch after its magnetic field had emerged from the accreted plasma due to diffusion. In the frame of this scenario AE Aqr represents a missing link in the chain of Polars evolution and the white dwarf resembles a recycled pulsar.

  13. Implementation of Multi Mode AES Algorithm Using Verilog

    Directory of Open Access Journals (Sweden)

    P Penchala Reddy

    2014-12-01

    Full Text Available Increasing need of high security in communication led to the development of several cryptographic algorithms hence sending data securely over a transmission link is critically important in many applications. NIST in the beginning selected Rijndael within October 2000 and formal adoption as being the AES standard started in December 2001. FIPS PUB 197 explains a 128-bit block cipher making Ause of a 128, 192, or 256-bit key. In cryptography, modes of operation enable the repeated and secure use of a block cipher under a single key. This paper presents implementation of multi mode AES algorithm with three modes ECB, CBC and CTR modes. All these three modes are implemented with 128-bit plain text and 128 bit, 192 bit and 256 bit key lengths. Each program results are verified with ModelSim PE and are synthesized in Xilinx ISE 9.2i. These results are also useful for implementing hardware.

  14. Formation of wormlike micelles in anionic surfactant AES aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The growth and structure of anionic micelles of sodium dodecyl trioxyethylene sulfate (AES) in the presence 3+of multivalent counterion Al were investigated by means of dynamic rheological methods. It has been obtained by the measurements of shear viscosity, complex viscosity and dynamic moduli, as well as the application of Cox-Merz rule and Cole-Cole plot that wormlike micelle and network structure could be formed in AES/AlCl3 aqueous solutions.The structure was of a character of nonlinear viscoelastic fluid and departure from the simple Maxwell model. The technique of freeze-fracture transmission electron microscopy (FF-TEM) was also used to confirm the formation of this interesting structure.``

  15. Efficient Hardware Design and Implementation of AES Cryptosystem

    Directory of Open Access Journals (Sweden)

    Pravin B. Ghewari

    2010-03-01

    Full Text Available We propose an efficient hardware architecture design & implementation of Advanced Encryption Standard (AES-Rijndael cryptosystem. The AES algorithm defined by the National Institute of Standard and Technology(NIST of United States has been widely accepted. The cryptographic algorithms can be implemented with software or built with pure hardware. However Field Programmable Gate Arrays (FPGA implementation offers quicker solution and can be easily upgraded to incorporate any protocol changes. This contribution investigates the AES encryption and decryption cryptosystem with regard to FPGA and Very High Speed Integrated Circuit Hardware Description language (VHDL. Optimized and Synthesizable VHDL code is developed for theimplementation of both 128- bit data encryption and decryption process. Xilinx ISE 8.1 software is used for simulation. Each program is tested with some of the sample vectors provided by NIST and output results are perfect with minimal delay. The throughput reaches the value of 352 Mbit/sec for both encryption and decryption process with Device XCV600 of Xilinx Virtex Family.

  16. Effective Comparison and Evaluation of DES and Rijndael Algorithm (AES

    Directory of Open Access Journals (Sweden)

    Prof.N..Penchalaiah,

    2010-08-01

    Full Text Available This paper discusses the effective coding of Rijndael algorithm, Advanced Encryption Standard (AES in Hardware Description Language, Verilog. In this work we analyze the structure and design of new AES, following three criteria: a resistance against all known attacks; b speed and code compactness on a wide range of platforms; and c designsimplicity; as well as its similarities and dissimilarities with other symmetric ciphers. On the other side, the principal advantages of new AES with respect to DES, as well as its limitations, are investigated. Thus, for example, the fact that the new cipher and its inverse use different components, which practically eliminates the possibility for weak and semi-weak keys, as existing for DES, and the non-linearity of the key expansion, which practically eliminates the possibility of equivalent keys, are two of the principal advantages of new cipher. Finally, the implementation aspects of Rijndael cipherand its inverse are treated. Thus, although Rijndael is well suited to be implemented efficiently on a wide range of processors and in dedicated hardware, we have concentrated our study on 8-bit processors, typical for current Smart Cards and on 32-bit processors, typical for PCs.

  17. Multifrequency Acoustic Emissions (AE) for Monitoring the Time Evolution of Microprocesses within Solids

    Science.gov (United States)

    Paparo, Gabriele; Gregori, Giovanni P.

    2003-03-01

    Microprocesses occur like chain reactions where bonds progressively yield. The temporal evolution can be tracked by multifrequency AE. Two principle ideas. One relies on time series of AE of increasingly lower frequency. The second compares time histories of every AE event (fixed frequency) with a lognormal distribution: deviations reveal additional parameters, and the tail results modulated by external effects, envisaging what triggers every AE. Natural environmental phenomena are effective feasibility tests, for subsequent laboratory implementation.

  18. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star.......Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star....

  19. 15 CFR 758.1 - The Shipper's Export Declaration (SED) or Automated Export System (AES) record.

    Science.gov (United States)

    2010-01-01

    ...) or Automated Export System (AES) record. 758.1 Section 758.1 Commerce and Foreign Trade Regulations... (SED) or Automated Export System (AES) record. (a) The Shipper's Export Declaration (SED) or Automated Export System (AES) record. The SED (Form 7525-V, Form 7525-V-Alt, or Automated Export System record)...

  20. Massive Stars

    Science.gov (United States)

    Livio, Mario; Villaver, Eva

    2009-11-01

    Participants; Preface Mario Livio and Eva Villaver; 1. High-mass star formation by gravitational collapse of massive cores M. R. Krumholz; 2. Observations of massive star formation N. A. Patel; 3. Massive star formation in the Galactic center D. F. Figer; 4. An X-ray tour of massive star-forming regions with Chandra L. K. Townsley; 5. Massive stars: feedback effects in the local universe M. S. Oey and C. J. Clarke; 6. The initial mass function in clusters B. G. Elmegreen; 7. Massive stars and star clusters in the Antennae galaxies B. C. Whitmore; 8. On the binarity of Eta Carinae T. R. Gull; 9. Parameters and winds of hot massive stars R. P. Kudritzki and M. A. Urbaneja; 10. Unraveling the Galaxy to find the first stars J. Tumlinson; 11. Optically observable zero-age main-sequence O stars N. R. Walborn; 12. Metallicity-dependent Wolf-Raynet winds P. A. Crowther; 13. Eruptive mass loss in very massive stars and Population III stars N. Smith; 14. From progenitor to afterlife R. A. Chevalier; 15. Pair-production supernovae: theory and observation E. Scannapieco; 16. Cosmic infrared background and Population III: an overview A. Kashlinsky.

  1. NuSTAR and swift observations of the fast rotating magnetized white dwarf AE Aquarii

    DEFF Research Database (Denmark)

    Kitaguchi, Takao; An, Hongjun; Beloborodov, Andrei M.;

    2014-01-01

    model with two temperatures of 1.00(-0.23)(+0.34) and 4.64(-0.84)(+1.58) keV plus a power-law component with photon index of 2.50(-0.23)(+0.17). The pulse profile in the 3-20 keV band is broad and approximately sinusoidal, with a pulsed fraction of 16.6% +/- 2.3%. We do not find any evidence...

  2. Hadron star models. [neutron stars

    Science.gov (United States)

    Cohen, J. M.; Boerner, G.

    1974-01-01

    The properties of fully relativistic rotating hadron star models are discussed using models based on recently developed equations of state. All of these stable neutron star models are bound with binding energies as high as about 25%. During hadron star formation, much of this energy will be released. The consequences, resulting from the release of this energy, are examined.

  3. Improving diffusion power of AES Rijndael with 8x8 MDS matrix

    Directory of Open Access Journals (Sweden)

    R.Elumalai,

    2011-01-01

    Full Text Available AES Rijndael is a block cipher developed by NIST as the Advanced Encryption Standard (AES replacing DES and published as FIPS 197 in November 2001 [5] to address the threatened key size of Data Encryption Standard (DES. AES-Rijndael was developed by Joan Daemen and Vincent Rijmen, Rijndael [4, 5] and was selected from five finalists. Advancement in computation speed every day puts lotsof pressure on AES and AES may not with stand attack for longer time. This work focuses on improving security of an encryption algorithm, beyond AES. Though there are various techniques available to enhance the security, an attempt is made to improve the diffusion strength of an algorithm. For enhancing the diffusion power AES Rijndael in MixColumn operation the branch number of MDS matrix is raised from 5 to 9 using a new 8X8 MDS matrix with trade off of speed [8, 9] and implemented on R8C microcontroller.

  4. "Storms of crustal stress" and AE earthquake precursors

    Directory of Open Access Journals (Sweden)

    G. P. Gregori

    2010-02-01

    Full Text Available Acoustic emission (AE displays violent paroxysms preceding strong earthquakes, observed within some large area (several hundred kilometres wide around the epicentre. We call them "storms of crustal stress" or, briefly "crustal storms". A few case histories are discussed, all dealing with the Italian peninsula, and with the different behaviour shown by the AE records in the Cephalonia island (Greece, which is characterized by a different tectonic setting.

    AE is an effective tool for diagnosing the state of some wide slab of the Earth's crust, and for monitoring its evolution, by means of AE of different frequencies. The same effect ought to be detected being time-delayed, when referring to progressively lower frequencies. This results to be an effective check for validating the physical interpretation.

    Unlike a seismic event, which involves a much limited focal volume and therefore affects a restricted area on the Earth's surface, a "crustal storm" typically involves some large slab of lithosphere and crust. In general, it cannot be easily reckoned to any specific seismic event. An earthquake responds to strictly local rheological features of the crust, which are eventually activated, and become crucial, on the occasion of a "crustal storm". A "crustal storm" lasts typically few years, eventually involving several destructive earthquakes that hit at different times, at different sites, within that given lithospheric slab.

    Concerning the case histories that are here discussed, the lithospheric slab is identified with the Italian peninsula. During 1996–1997 a "crustal storm" was on, maybe elapsing until 2002 (we lack information for the period 1998–2001. Then, a quiet period occurred from 2002 until 26 May 2008, when a new "crustal storm" started, and by the end of 2009 it is still on. During the 1996–1997 "storm" two strong earthquakes occurred (Potenza and

  5. Evolution of emission line activity in intermediate mass young stars

    CERN Document Server

    Manoj, P; Maheswar, G; Muneer, S

    2006-01-01

    We present optical spectra of 45 intermediate mass Herbig Ae/Be stars. Together with the multi-epoch spectroscopic and photometric data compiled for a large sample of these stars and ages estimated for individual stars by using pre-main sequence evolutionary tracks, we have studied the evolution of emission line activity in them. We find that, on average, the H_alpha emission line strength decreases with increasing stellar age in HAeBe stars, indicating that the accretion activity gradually declines during the PMS phase. This would hint at a relatively long-lived (a few Myr) process being responsible for the cessation of accretion in Herbig Ae/Be stars. We also find that the accretion activity in these stars drops substantially by ~ 3 Myr. This is comparable to the timescale in which most intermediate mass stars are thought to lose their inner disks, suggesting that inner disks in intermediate mass stars are dissipated rapidly after the accretion activity has fallen below a certain level. We, further find a r...

  6. Chemical analysis of 24 dusty (pre-)main-sequence stars

    CERN Document Server

    Acke, B; Acke, Bram; Waelkens, Christoffel

    2004-01-01

    We have analysed the chemical photospheric composition of 24 Herbig Ae/Be and Vega-type stars in search for the lambda Bootis phenomenon. We present the results of the elemental abundances of the sample stars. Some of the stars were never before studied spectroscopically at optical wavelengths. We have determined the projected rotational velocities of our sample stars. Furthermore, we discuss stars that depict a (selective) depletion pattern in detail. HD 4881 and HD 139614 seem to display an overall deficiency. AB Aur and possibly HD 126367 have subsolar values for the iron abundance, but are almost solar in silicon. HD 100546 is the only clear lambda Bootis star in our sample.

  7. Star Wreck

    OpenAIRE

    Kusenko, Alexander; Shaposhnikov, Mikhail E.; Tinyakov, P. G.; Tkachev, Igor I.

    1998-01-01

    Electroweak models with low-energy supersymmetry breaking predict the existence of stable non-topological solitons, Q-balls, that can be produced in the early universe. The relic Q-balls can accumulate inside a neutron star and gradually absorb the baryons into the scalar condensate. This causes a slow reduction in the mass of the star. When the mass reaches a critical value, the neutron star becomes unstable and explodes. The cataclysmic destruction of the distant neutron stars may be the or...

  8. Star polygons

    OpenAIRE

    Riosa, Blažka

    2014-01-01

    In mathematics we often encounter polygons, such us triangle, square, hexagon, etc., but we hardly encounter star polygons. Despite the fact that we do not meet them so often in mathematics, in nature they can be traced almost on every step. In this paper the emphasis is on the geometric meaning of regular star polygons. Star polygon is a generalization of the concept of regular polygons. In star polygons also non-adjacent sides intersect. Up to similarity they are determined by Schläfli symb...

  9. STAR Calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, W W, E-mail: jacobsw@indiana.ed [Indiana University Cyclotron Facility and Department of Physics, 2401 Milo B. Sampson Lane, Bloomington IN 47408 (United States)

    2009-04-01

    The main STAR calorimeters comprise a full Barrel EMC and single Endcap EMC plus a Forward Meson Spectrometer. Together they give a nearly complete coverage over the range -1 < pseudorapidity < 4 and provide EM readout and triggering that help drive STAR physics capabilities. Their description, status, performance and operations (and a few physics anecdotes) are briefly presented and discussed.

  10. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star.......Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star....

  11. Star Imager

    DEFF Research Database (Denmark)

    Madsen, Peter Buch; Jørgensen, John Leif; Thuesen, Gøsta;

    1997-01-01

    The version of the star imager developed for Astrid II is described. All functions and features are described as well as the operations and the software protocol.......The version of the star imager developed for Astrid II is described. All functions and features are described as well as the operations and the software protocol....

  12. Implementation of AES as a Custom Hardware using NIOS II Processor

    Directory of Open Access Journals (Sweden)

    Meghana Hasamnis

    2012-08-01

    Full Text Available In this paper Advanced Encryption Standard (AES algorithm has been designed and implemented as custom hardware. The algorithm is controlled through C-code written in NIOS II IDE. AES as a custom hardware is interfaced with the system designed around NIOS II Processor using SOPC builder tool. AES is written in hardware in VHDL language and the interface is through GPIO (General Purpose Input / Output Port. AES implemented using data size of 128 bits, while the length of the key used is of 128 bits. The key size of AES used is of 128 bits, as it is secure from the different attacks in existence. The FPGA used is CYCLONE II from Altera. AES as a custom hardware increases the speed of encryption and serves as an accelerator and hence improves the performance of the system.

  13. A Lossless Data Hiding Technique based on AES-DWT

    Directory of Open Access Journals (Sweden)

    Gustavo Fernandaacute;ndez Torres2

    2012-09-01

    Full Text Available In this paper we propose a new data hiding technique. The new technique uses steganography and cryptography on images with a size of 256x256 pixels and an 8-bit grayscale format. There are design restrictions such as a fixed-size cover image, and reconstruction without error of the hidden image. The steganography technique uses a Haar-DWT (Discrete Wavelet Transform with hard thresholding and LSB (Less Significant Bit technique on the cover image. The algorithms used for compressing and ciphering the secret image are lossless JPG and AES, respectively. The proposed technique is used to generate a stego image which provides a double type of security that is robust against attacks. Results are reported for different thresholds levels in terms of PSNR.

  14. NPS alternate techsat satellite, design project for AE-4871

    Science.gov (United States)

    1993-01-01

    This project was completed as part of AE-4871, Advanced Spacecraft Design. The intent of the course is to provide experience in the design of all the major components in a spacecraft system. Team members were given responsibility for the design of one of the six primary subsystems: power, structures, propulsion, attitude control, telemetry, tracking and control (TT&C), and thermal control. In addition, a single member worked on configuration control, launch vehicle integration, and a spacecraft test plan. Given an eleven week time constraint, a preliminary design of each subsystem was completed. Where possible, possible component selections were also made. Assistance for this project came principally from the Naval Research Laboratory's Spacecraft Technology Branch. Specific information on components was solicited from representatives in industry. The design project centers on a general purpose satellite bus that is currently being sought by the Strategic Defense Initiative.

  15. Role of AE2 for pHi regulation in biliary epithelial cells

    Directory of Open Access Journals (Sweden)

    Axel R. Concepcion

    2014-01-01

    Full Text Available The Cl-/HCO3- anion exchanger 2 (AE2 is known to be involved in intracellular pH (pHi regulation and transepithelial acid-base transport. Early studies showed that AE2 gene expression is reduced in liver biopsies and blood mononuclear cells from patients with primary biliary cirrhosis (PBC, a disease characterized by chronic nonsuppurative cholangitis associated with antimitochondrial antibodies (AMA and other autoimmune phenomena. Microfluorimetric analysis of the Cl-/HCO3- anion exchange (AE in isolated cholangiocytes showed that the cAMP-stimulated AE activity is diminished in PBC compared to both healthy and diseased controls. More recently, it was found that miR-506 is upregulated in cholangiocytes of PBC patients and that AE2 may be a target of miR-506. Additional evidence for a pathogenic role of AE2 dysregulation in PBC was obtained with Ae2a,b-/- mice, which develop biochemical, histological, and immunologic alterations that resemble PBC (including development of serum AMA. Analysis of HCO3- transport systems and pHi regulation in cholangiocytes from normal and Ae2a,b-/- mice confirmed that AE2 is the transporter responsible for the Cl–/HCO3– exchange in these cells. On the other hand, both Ae2a,b+/+ and Ae2a,b-/- mouse cholangiocytes exhibited a Cl--independent bicarbonate transport system, essentially a Na+-bicarbonate cotransport (NBC system, which could contribute to pHi regulation in the absence of AE2.

  16. Comportamento de Aedes albopictus e de Ae. scapularis adultos (Diptera: Culicidae no Sudeste do Brasil Adults Aedes albopictus and Ae. scapularis behavior (Diptera: Culidae in Southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Oswaldo Paulo Forattini

    2000-10-01

    Full Text Available OBJETIVO: Observar e comparar o comportamento das espécies de Aedes albopictus e de Ae. scapularis, na localidade de Pedrinhas, litoral sul do Estado de São Paulo, Brasil. MÉTODOS: As observações foram feitas de outubro de 1996 a janeiro de 2000. Foram realizadas coletas sistemáticas de formas adultas mediante a utilização de isca humana, aspirações ambientais e armadilha tipo Shannon. A domiciliação foi estimada pelo índice de Nuorteva e pela razão de sinantropia. RESULTADOS: Foram feitas 87 coletas diurnas, com a obtenção de 872 adultos fêmeas. As médias de Williams', multiplicadas por 100, foram de 118 e 21 para Ae. albopictus nos horários de 7h às 18h e de 18h às 20h, respectivamente. Quanto a Ae. scapularis, foram de 100 e 106 nos mesmos períodos. Esse último revelou pico de atividade crepuscular vespertina. Na aspiração de abrigos, obteve-se o total de 1.124 espécimens, dos quais 226 Ae. albopictus e 898 Ae. scapularis. O período de janeiro a maio correspondeu ao de maior rendimento para ambos os mosquitos. Quanto à armadilha de Shannon, as coletas realizadas na mata revelaram a ausência de Ae. albopictus. No que concerne à domiciliação, esse último mostrou os maiores valores de índices, enquanto Ae. scapularis revelou comportamento de tipo ubiquista. CONCLUSÕES: Os resultados confirmam outras observações, permitindo levantar hipóteses. Em relação a Ae. scapularis, sugere-se que possa existir fenômeno de diapausa das fêmeas no período verão-outono, a qual cessaria no inverno-primavera quando então a atividade seria retomada. Quanto a Ae. albopictus, os dados sugerem que se trata de população em processo adaptativo ao novo ambiente.OBJECTIVE: Aedes albopictus and Ae. scapularis were found living together in the Pedrinhas Village, Southeastern of São Paulo State, Brazil. This finding was a good opportunity to make observations about the mosquitoes' behavior. METHODS: From October 1996 to

  17. Analysis of Fracture Signals from Tooth/Composite Restoration According to AE Sensor Attachment

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Ja Uk; Choi, Nak Sam [Hanyang University, Ansan (Korea, Republic of)

    2011-10-15

    Acoustic emission(AE) signals during the polymerization shrinkage of composite resin subjected to the LED light exposure were detected through a wave guide method and a direct sensor attachment method. For PMMA, human tooth, stainless steel substrate, data of AE hits and amplitudes were compared. For the test using the wave guide, AE amplitudes decreased because of the attenuant wave. However, AE hits and 1st peak frequency distribution were not different according to the sensor attachments. Through the experiments, wave guide could be used for a nondestructive evaluation of the marginal disintegrative fracture of dental restoration.

  18. Low-area hardware implementations of CLOC, SILC and AES-OTR

    DEFF Research Database (Denmark)

    Banik, Subhadeep; Bogdanov, Andrey; Minematsu, Kazuhiko

    2016-01-01

    as the underlying block cipher, we investigate if they can be implemented in a compact fashion using the 8-bit serialized AES circuit. In this context we investigate three authenticated encryption modes CLOC, SILC and AES-OTR. Using the standard cell library of the STM 90nm process, we implemented CLOC and SILC......The most compact implementation of the AES-128 algorithm was the 8-bit serial circuit proposed in the work of Moradi et. al. (Eurocrypt 2011). The circuit has an 8-bit datapath and occupies area equivalent to around 2400 GE. Since many authenticated encryption modes use the AES-128 algorithm...

  19. Superlattice origin of incommensurable density waves in $La__{2-x}Ae_xCuO4$ (Ae = Ba, Sr)

    CERN Document Server

    Bucher, Manfred

    2013-01-01

    In line with the Coulomb-oscillator model of superconductivity, loop currents of excited 3s electrons from O^2- ions, passing in the CuO2 plane through nuclei of nearest-neighbor oxygen quartets, create the antiferromagnetic phase of undoped copper oxides. Holes, introduced by alkaline-earth doping of La2CuO4, destroy the loop currents, thereby weakening antiferromagnetism until it disappears at doping x = 0.02. Further doping of La_2-xAe_xCuO4 gives rise to incommensurate free-hole density waves whose wavelength is determined by the spacing of a doping superlattice. Modulating the ordering of the ions' magnetic moments, the charge-density wave, of incommensurability 2 delta, causes a magnetic density wave of incommensurability delta. The formula derived for delta(x) is in excellent agreement with data from X-ray diffraction and neutron scattering.

  20. Spontaneous wheat-Aegilops biuncialis, Ae. geniculata and Ae. triuncialis amphiploid production, a potential way of gene transference

    Energy Technology Data Exchange (ETDEWEB)

    Loureiro, I.; Escorial, C.; Garcia-Baudin, J. M.; Chueca, M. C.

    2009-07-01

    Some F1 hybrid plants between three species of the Aegilops genus and different hexaploid wheat Triticum aestivum cultivars show certain self-fertility, with averages of F{sub 1} hybrids bearing F{sub 2} seeds of 8.17%, 5.12% and 48.14% for Aegilops biuncialis, Aegilops geniculata and Aegilops triuncialis respectively. In the Ae. triuncialis-wheat combination with Astral wheat cultivar, the fertility was higher than that found in the other combinations. All the F2 seeds studied were spontaneous amphiploids (2n=10x=70). The present study evidences the possibility of spontaneous formation of amphiploids between these three Aegilops species and hexaploid wheat and discusses their relevance for gene transference. Future risk assessment of transgenic wheat cultivars needs to evaluate the importance of amphiploids as a bridge for transgene introgression and for gene escape to the wild. (Author)

  1. From neutron stars to quark stars in mimetic gravity

    CERN Document Server

    Astashenok, A V

    2015-01-01

    Realistic models of neutron and quark stars in the framework of mimetic gravity with Lagrange multiplier constraint are presented. We discuss the effect of mimetic scalar aiming to describe dark matter on mass-radius relation and the moment of inertia for slowly rotating relativistic stars. The mass-radius relation and moment of inertia depend on the value of mimetic scalar in the center of star. This fact leads to the ambiguity in the mass-radius relation for a given equation of state. {Such ambiguity allows to explain some observational facts better than in standard General Relativity}. The case of two mimetic potentials namely $V(\\phi)\\sim A\\phi^{-2}$ and $V(\\phi)\\sim Ae^{B\\phi^{2}}$ is considered in detail. The relative deviation of maximal moment of inertia is approximately twice larger than the relative deviation of maximal stellar mass. We also briefly discuss the mimetic $f(R)$ gravity. In the case of $f(R)=R+aR^2$ mimetic gravity it is expected that increase of maximal mass and maximal moment of iner...

  2. Rising Star

    OpenAIRE

    Worley, Christiana

    2012-01-01

    Rising Star is a novel about appearances. Thailand Allen is a girl who thinks she understands what she sees. But when what she sees are cracks in her perfect world, maturation and new sight are not far off. Before growth can occur, Thailand must undergo a painful process of learning that carries with it embarrassment, sorrow, anger and confusion. Thailand lives with her mother in a small Texas town called Rising Star. Rising Star is like every other small town with its community gather...

  3. Characterization of low-molecular-weight-glutenin subunit genes from the D-genome of Triticum aestivum, Aegilops crassa, Ae. cylindrica and Ae. tauschii

    NARCIS (Netherlands)

    Naghavi, M.R.; Ahmadi, S.; Shanejat-Boushehri, A.A.; Komaei, G.; Struik, P.C.

    2013-01-01

    Twenty low-molecular-weight-glutenin subunit (LMW-GS) gene sequences from the D-genome from Aegilops crassa (2n ¼ 4x ¼ 28), Ae. cylindrica (2n ¼ 4x ¼ 28), Ae. tauschii (2n ¼ 2x ¼ 14) and Triticum aestivum (2n ¼ 6x ¼ 42) were obtained using five sets of specific allele primer pairs. Only the sequence

  4. Theoretical characterization of quaternary iridium based hydrides NaAeIrH{sub 6} (Ae = Ca, Ba and Sr)

    Energy Technology Data Exchange (ETDEWEB)

    Bouras, S. [Laboratory of Studies Surfaces and Interfaces of Solids Materials, Department of Physics, Faculty of Science, University of Setif 1, 19000 (Algeria); Ghebouli, B., E-mail: bghebouli@yahoo.fr [Laboratory of Studies Surfaces and Interfaces of Solids Materials, Department of Physics, Faculty of Science, University of Setif 1, 19000 (Algeria); Benkerri, M. [Laboratory of Studies Surfaces and Interfaces of Solids Materials, Department of Physics, Faculty of Science, University of Setif 1, 19000 (Algeria); Ghebouli, M.A., E-mail: med.amineghebouli@yahoo.fr [Microelectronic Laboratory (LMSE), University of Bachir Ibrahimi, Bordj-Bou-Arreridj 34000 (Algeria); Research Unit on Emerging Materials (RUEM), University of Setif 1, 19000 (Algeria); Choutri, H. [Microelectronic Laboratory (LMSE), University of Bachir Ibrahimi, Bordj-Bou-Arreridj 34000 (Algeria); Louail, L.; Chihi, T.; Fatmi, M. [Research Unit on Emerging Materials (RUEM), University of Setif 1, 19000 (Algeria); Bouhemadou, A. [Laboratory for Developing New Materials and Their Characterization, Department of Physics, Faculty of Science, University of Setif 1, 19000 (Algeria); Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Khenata, R.; Khachai, H. [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 (Algeria)

    2015-01-15

    The quaternary iridium based hydrides NaAeIrH{sub 6} (Ae = Ca, Ba and Sr) are promising candidates as hydrogen storage materials. We have studied the structural, elastic, electronic, optical and thermodynamic properties of NaAeIrH{sub 6} (Ae = Ca, Ba and Sr) within the generalized gradient approximation, the local density approximation (LDA) and mBj in the frame of density functional perturbation theory. These alloys have a large indirect Γ–X band gap. The thermodynamic functions were computed using the phonon density of states. The origin of the possible transitions from valence band to conduction band was illustrated. By using the complex dielectric function, the optical properties such as absorption, reflectivity, loss function, refractive index and optical conductivity have been obtained. - Graphical abstract: Real and imaginary parts of the dielectric function, the absorption spectrum α(ω), reflectivity R(ω) and energy-loss spectrum L(ω). - Highlights: • NaAeIrH{sub 6} (Ae = Ca, Ba and Sr) alloys have been investigated. • The elastic moduli, energy gaps are predicted. • The optical and thermal properties were studied.

  5. Carbon Stars

    Indian Academy of Sciences (India)

    T. Lloyd Evans

    2010-12-01

    In this paper, the present state of knowledge of the carbon stars is discussed. Particular attention is given to issues of classification, evolution, variability, populations in our own and other galaxies, and circumstellar material.

  6. Rock Stars

    Institute of Scientific and Technical Information of China (English)

    张国平

    2000-01-01

    Around the world young people are spending unbelievable sums of money to listen to rock music. Forbes Magazine reports that at least fifty rock stars have incomes between two million and six million dollars per year.

  7. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter

    Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star....

  8. STAR POLYMERS

    OpenAIRE

    Ch. von Ferber; Yu.Holovatch

    2002-01-01

    It is our great pleasure to present a collection of papers devoted to theoretical, numerical, and experimental studies in the field of star polymers. Since its introduction in the early 80-ies, this field has attracted increasing interest and has become an important part of contemporary polymer physics. While research papers in this field appear regularly in different physical and chemical journals, the present collection is an attempt to join together the studies of star polymers showing the...

  9. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Andersen, Thomas Lykke

    Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star....

  10. Phylogenetic and temporal dynamics of human immunodeficiency virus type 1 CRF01_AE in China.

    Directory of Open Access Journals (Sweden)

    Jingrong Ye

    Full Text Available To explore the epidemic history of HIV-1 CRF01_AE in China, 408 fragments of gag gene sequences of CRF01_AE sampled in 2002-2010 were determined from different geographical regions and risk populations in China. Phylogenetic analysis indicates that the CRF01_AE sequences can be grouped into four clusters, suggesting that at least four genetically independent CRF01_AE descendants are circulating in China, of which two were closely related to the isolates from Thailand and Vietnam. Cluster 1 has the most extensive distribution in China. In North China, cluster 1 and cluster 4 were mainly transmitted through homosexuality.The real substance of the recent HIV-1 epidemic in men who have sex with men(MSM of North China is a rapid spread of CRF01_AE, or rather two distinctive natives CRF01_AE.The time of the most recent common ancestor (tMRCA of four CRF01_AE clusters ranged from the years 1990.9 to 2003.8 in different regions of China. This is the first phylogenetic and temporal dynamics study of HIV-1 CRF01_AE in China.

  11. 15 CFR Appendix D to Part 30 - AES Filing Citation, Exemption and Exclusion Legends

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false AES Filing Citation, Exemption and Exclusion Legends D Appendix D to Part 30 Commerce and Foreign Trade Regulations Relating to Commerce and... Appendix D to Part 30—AES Filing Citation, Exemption and Exclusion Legends I. USML Proof of Filing...

  12. One AES S-box to increase complexity and its cryptanalysis

    Institute of Scientific and Technical Information of China (English)

    Liu Jingmei; Wei Baodian; Wang Xinmei

    2007-01-01

    It is well known that the algebraic expression of AES S-box is very simple and only 9 terms are involved.Hence, AES security is suspected although there is no vulnerability on it so far.To eliminate the weakness of extremely small terms in the algebraic expression of AES S-box, one improved AES S-box is proposed, which preserves the algebraic degree invariable but significantly increases the number of its algebraic expression terms from 9 to 255.At the same time, Boolean function has good characters in balance and strict avalanche criterion (SAC), etc.Finally, it is proved that the improved AES S-box scheme is secure against the powerful known differential and linear cryptanalysis.

  13. Accurate quantification of Cu(In,Ga)Se{sub 2} films by AES depth profiling analysis

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jong Shik [Division of Industrial Metrology, Korea Research Institute of Standards and Science (KRISS), 267, Gajeong-ro, Yuseong-gu, Daejeon (Korea, Republic of); Department of Physics, Chungbuk National University, 52 Naesudong-ro, Heungdeok-gu, Cheongju, Chungbuk 361-763 (Korea, Republic of); Hwang, Hye Hyen [Division of Industrial Metrology, Korea Research Institute of Standards and Science (KRISS), 267, Gajeong-ro, Yuseong-gu, Daejeon (Korea, Republic of); Kang, Hee Jae [Department of Physics, Chungbuk National University, 52 Naesudong-ro, Heungdeok-gu, Cheongju, Chungbuk 361-763 (Korea, Republic of); Chae, Hong-Chol [Center for Research Instruments and Experimental Facilities, Chungbuk National University, 52 Naesudong-ro, Heungdeok-gu, Cheongju, Chungbuk 361-763 (Korea, Republic of); Chung, Yong-Duck [Advanced Solar Tech Dept, Electronics and Telecommunications Research Institute (ETRI), 218, Gajeong-ro, Yuseong-gu, Daejeon (Korea, Republic of); Kim, Kyung Joong, E-mail: kjkim@kriss.re.kr [Division of Industrial Metrology, Korea Research Institute of Standards and Science (KRISS), 267, Gajeong-ro, Yuseong-gu, Daejeon (Korea, Republic of); Department of Nano Science, Korea University of Science and Technology, 217, Gajeong-ro, Yuseong-gu, Daejeon (Korea, Republic of)

    2013-10-01

    Quantitative analysis of Cu(In,Ga)Se{sub 2} (CIGS) films with non-uniform depth distributions was investigated by Auger electron spectroscopy (AES) depth profiling. The atomic fractions of the CIGS films were measured by relative sensitivity factors determined by a total number counting method from a CIGS reference film certified by isotope dilution–inductively coupled plasma/mass spectrometry. In the AES depth profiling analysis of the CIGS films, the intensities of Auger electron peaks in Cu, In, Ga and Se were determined by integrating the individual Auger peak intensities in the whole depth range of the AES depth profiles. The atomic fractions measured by AES analysis were linearly proportional to the certified values. The uncertainty in the AES depth profiling analysis of CIGS films was much smaller than that in the secondary ion mass spectrometry depth profiling analysis and that in the international comparison of national metrology institutes for the quantification of Fe–Ni alloy films.

  14. Detection of Staphylococcus Aureus Enterotoxin Genes A-E

    Directory of Open Access Journals (Sweden)

    Dadgar, T. (PhD

    2014-06-01

    Full Text Available Background and Objective: The main cause of spreading staphylococcal infections among patients is the healthy carriers working in hospitals. With the secretion of different sorts of toxins such as entrotoxin, this bacteria can provide the conditions for attacking on the host. The main objective of this study is identification of the characteristics and differences in the Staphylococcus aureus isolated from healthy carriers and from the patients on the basis of enterotoxin genes (sea-see. Material and Methods: One hundred and twenty of the patients and 80 of healthy carriers worked in health centers of Gorgan, north of Iran, were investigated for S. aureus isolate. The isolates were evaluated by PCR for Enterotoxin Genes A-E (SEA to SEE. Results: Enterotoxin genes (SEA to SEE was found in 87.5% of the total isolates and the most frequent one was enterotoxin gene sea (N= 124. The prevalence of these isolates in healthy carriers was significantly higher than those of the patients. Conclusion: Based on the results, the high percentage of S. aureus isolated from clinical samples contains enterotoxin genes. Therefore, Human as the source and carrier of S. aureus is paramount importance, which is due to significant relationship between being toxigenic strains and the source of isolation. Key words: Staphylococcus Aureus; Enterotoxin; Patient; Carrier

  15. Estudio espectroscópico y fotométrico de candidatas a estrellas Herbig AeBe

    Science.gov (United States)

    Giuppone, C. A.; Rodón, J. A.; Yapura, O.; Yaryura, C. Y.

    A photometric study of the candidates to Herbig AeBe stars EM LKHA 108, NGC 6530 151 and NGC 6530 45 from the open cluster NGC 6530 was started. This study is part of a wider effort intended to confirm the membership to this class of these stars. Direct images were taken at Complejo Astronómico El Leoncito with the 215 cm telescope and filters B and V. The reduction to the Johnson UBV system was performed with the noao.imred package of IRAF, while the aperture photometry was accomplished with the digiphot.apphot package. The apparent magnitudes and colors obtained were, for EM LKHA 108: V=14.6, σV=1.1, (B-V)=1.0, σ(B-V)=0.1; for NGC 6530 151: V=11.8, σV=0.1, (B-V)=0.69, σ(B-V)=0.05; and for NGC 6530 45: V=7.2, σV=0.1, (B-V)=1.27, σ(B-V)=0.09. The spectroscopic study could not be performed yet due to technical difficulties in obtaining the spectra.

  16. Identifying gaps in flaring Herbig Ae/Be disks using spatially resolved mid-infrared imaging. Are all group I disks transitional?

    CERN Document Server

    Maaskant, K M; Waters, L B F M; Tielens, A G G M; Dominik, C; Min, M; Verhoeff, A; Meeus, G; Ancker, M E van den

    2013-01-01

    *Context The evolution of young massive protoplanetary disks toward planetary systems is expected to include the formation of gaps and the depletion of dust and gas. *Aims A special group of flaring disks around Herbig Ae/Be stars do not show prominent silicate emission features. We focus our attention on four key Herbig Ae/Be stars to understand the structural properties responsible for the absence of silicate feature emission. *Methods We investigate Q- and N-band images taken with Subaru/COMICS, Gemini South/T-ReCS and VLT/VISIR. Our radiative transfer modeling solutions require a separation of inner- and outer- disks by a large gap. From this we characterize the radial density structure of dust and PAHs in the disk. *Results The inner edge of the outer disk has a high surface brightness and a typical temperature between ~100-150 K and therefore dominates the emission in the Q-band. We derive radii of the inner edge of the outer disk of 34, 23, 30 and 63 AU for HD97048, HD169142, HD135344B and Oph IRS 48 r...

  17. High-Energy X-Ray Detection of G359.89-0.08 (SGR A-E): Magnetic Flux Tube Emission Powered by Cosmic Rays?

    Science.gov (United States)

    Zhang, Shuo; Hailey, Charles J.; Baganoff, Frederick K.; Bauer, Franz E.; Boggs, Steven E.; Craig, William W.; Christensen, Finn E.; Gotthelf, Eric V.; Harrison, Fiona A.; Mori, Kaya; Nynka, Melania; Stern, Daniel; Tomsick, John A; Zhang, Will

    2014-01-01

    We report the first detection of high-energy X-ray (E (is) greater than 10 keV) emission from the Galactic center non-thermal filament G359.89-0.08 (Sgr A-E) using data acquired with the Nuclear Spectroscopic Telescope Array (NuSTAR). The bright filament was detected up to approximately 50 keV during a NuSTAR Galactic center monitoring campaign. The featureless power-law spectrum with a photon index gamma approximately equals 2.3 confirms a non-thermal emission mechanism. The observed flux in the 3-79 keV band is F(sub X) = (2.0 +/- 0.1) × 10(exp -12)erg cm(-2) s(-1) , corresponding to an unabsorbed X-ray luminosity L(sub X) = (2.6+/-0.8)×10(exp 34) erg s(-1) assuming a distance of 8.0 kpc. Based on theoretical predictions and observations, we conclude that Sgr A-E is unlikely to be a pulsar wind nebula (PWN) or supernova remnant-molecular cloud (SNR-MC) interaction, as previously hypothesized. Instead, the emission could be due to a magnetic flux tube which traps TeV electrons. We propose two possible TeV electron sources: old PWNe (up to (is) approximately 100 kyr) with low surface brightness and radii up to (is) approximately 30 pc or MCs illuminated by cosmic rays (CRs) from CR accelerators such as SNRs or Sgr A*.

  18. Morning Star

    OpenAIRE

    Harris, Mark

    2010-01-01

    Morning Star comprises a group of paintings and drawings whose imagery derives from photographs of 1960s American hippie communes. The paintings are made using oil paint on linen. Their dimensions vary between 180 x 120, and 228 x 217 centimetres. The drawings are in pencil on watercolour paper and are all 56 x 76 centimetres. The work has been exhibited in conventional form, hanging on gallery walls. For Morning Star I made pencil drawings and oil paintings derived from images in Dick Fa...

  19. Application of Normal Mode Expansion to AE Waves in Finite Plates

    Science.gov (United States)

    Gorman, M. R.; Prosser, W. H.

    1997-01-01

    Breckenridge et al. (1975), Hsu (1985) and Pao (1978) adapted approaches from seismology to calculate the response at the surface of an infinite half-space and an infinite plate. These approaches have found use in calibrating acoustic emission (AE) transducers. However, it is difficult to extend this theoretical approach to AE testing of practical structures. Weaver and Pao (1982) considered a normal mode solution to the Lamb equations. Hutchinson (1983) pointed out the potential relevance of Mindlin's plate theory (1951) to AE. Pao (1982) reviewed Medick s (1961) classical plate theory for a point source, but rejected it as useful for AE and no one seems to have investigated its relevance to AE any further. Herein, a normal mode solution to the classical plate bending equation was investigated for its applicability to AE. The same source-time function chosen by Weaver and Pao is considered. However, arbitrary source and receiver positions are chosen relative to the boundaries of the plate. This is another advantage of the plate theory treatment in addition to its simplicity. The source does not have to be at the center of the plate as in the axisymmetric treatment. The plate is allowed to remain finite and reflections are predicted. The importance of this theory to AE is that it can handle finite plates, realistic boundary conditions, and can be extended to composite materials.

  20. On the infant weight loss of low- to intermediate-mass star clusters

    Science.gov (United States)

    Weidner, C.; Kroupa, P.; Nürnberger, D. E. A.; Sterzik, M. F.

    2007-04-01

    Star clusters are born in a highly compact configuration, typically with radii of less than about 1 pc roughly independently of mass. Since the star formation efficiency is less than 50 per cent by observation and because the residual gas is removed from the embedded cluster, the cluster must expand. In the process of doing so it only retains a fraction fst of its stars. To date there are no observational constraints for fst, although N-body calculations by Kroupa, Aarseth & Hurley suggest it to be about 20-30 per cent for Orion-type clusters. Here we use the data compiled by Testi et al., Testi, Palla & Natta and Testi, Palla & Natta for clusters around young Ae/Be stars and by de Wit et al. and de Wit et al. around young O stars and the study of de Zeeuw et al. of OB associations and combine these measurements with the expected number of stars in clusters with primary Ae/Be and O stars, respectively, using the empirical correlation between maximal stellar mass and star cluster mass of Weidner & Kroupa. We find that fst < 50 per cent with a decrease to higher cluster masses/more massive primaries. The interpretation would be that cluster formation is very disruptive. It appears that clusters with a birth stellar mass in the range 10-103Msolar keep at most 50 per cent of their stars.

  1. Pseudomonas aeruginosa AES-1 exhibits increased virulence gene expression during chronic infection of cystic fibrosis lung.

    Directory of Open Access Journals (Sweden)

    Sharna Naughton

    Full Text Available Pseudomonas aeruginosa, the leading cause of morbidity and mortality in people with cystic fibrosis (CF, adapts for survival in the CF lung through both mutation and gene expression changes. Frequent clonal strains such as the Australian Epidemic Strain-1 (AES-1, have increased ability to establish infection in the CF lung and to superimpose and replace infrequent clonal strains. Little is known about the factors underpinning these properties. Analysis has been hampered by lack of expression array templates containing CF-strain specific genes. We sequenced the genome of an acute infection AES-1 isolate from a CF infant (AES-1R and constructed a non-redundant micro-array (PANarray comprising AES-1R and seven other sequenced P. aeruginosa genomes. The unclosed AES-1R genome comprised 6.254Mbp and contained 6957 putative genes, including 338 not found in the other seven genomes. The PANarray contained 12,543 gene probe spots; comprising 12,147 P. aeruginosa gene probes, 326 quality-control probes and 70 probes for non-P. aeruginosa genes, including phage and plant genes. We grew AES-1R and its isogenic pair AES-1M, taken from the same patient 10.5 years later and not eradicated in the intervening period, in our validated artificial sputum medium (ASMDM and used the PANarray to compare gene expression of both in duplicate. 675 genes were differentially expressed between the isogenic pairs, including upregulation of alginate, biofilm, persistence genes and virulence-related genes such as dihydroorotase, uridylate kinase and cardiolipin synthase, in AES-1M. Non-PAO1 genes upregulated in AES-1M included pathogenesis-related (PAGI-5 genes present in strains PACS2 and PA7, and numerous phage genes. Elucidation of these genes' roles could lead to targeted treatment strategies for chronically infected CF patients.

  2. Design and Hardware Implementation of QoSS - AES Processor for Multimedia applications

    Directory of Open Access Journals (Sweden)

    Zeghid Medien

    2010-04-01

    Full Text Available For real-time applications, there are several factors (time, cost, power that are moving security considerations from a function centric perspective into a system architecture (hardware/software design issue. Advanced Encryption Standard (AES is used nowadays extensively in many network and multimedia applications to address security issues. The AES algorithm specifies three key sizes: 128, 192 and 256 bits offering different levels of security. To deal with the amount of application and intensive computation given by security mechanisms, we define and develop a QoSS (Quality of Security Service model for reconfigurable AES processor. QoSS has been designed and implemented to achieve a flexible trade-off between overheads caused by security services and system performance. The proposed architecture can provide up to 12 AES block cipher schemes within a reasonable hardware cost. We envisage a security vector in a fully functional QoSS request to include levels of service for the range of security service and mechanisms. Our unified hardware can run both the original AES algorithm and the extended AES algorithm (QoSS-AES. A novel on-the-fly AES encryption/ decryption design is also proposed for 128- , 192- , and 256-bit keys. The performance of the proposed processor has been analyzed in an MPEG4 video compression standard. The results revealed that the QoSS-AES processor is well suited to provide high security communication with low latencies. In our implementation based on Xilinx Virtex FPGAs, speed/area/power results from these processors are analyzed and shown to compare favorably with other well known FPGA based implementations.

  3. Active Phenomena in the Pre-main Sequence Star AB AUR

    Science.gov (United States)

    Praderie, F.; Simon, T.; Boesgaard, A. M.; Felenbok, P.; Catala, C.; Czarny, J.; Talavera, A.

    1985-01-01

    The Herbig Ae star AB Aur presents short time scale variability in the Mg II and Ca II resonance lines. A qualitative model of the expanding envelope, involving fast and slow streams in a co-rotating structure, is proposed to explain the Mg II spectral variability.

  4. Design of Host Bus Adapter Based on FC-AE-ASM%基于FC-AE-ASM协议主机总线适配器设计

    Institute of Scientific and Technical Information of China (English)

    袁新治

    2016-01-01

    FC-AE-ASM协议是FC-AE网络中的一种上层协议,研究FC-AE-ASM网络的主机总线适配器具有重要的意义.本文对FC-AE协议以及ASM协议进行分析,设计并实现一种FC-AE-ASM网络的主机总线适配器,并从FC-AE协议主机总线适配器的系统结构设计、ASM消息收发机制等方面对该设计说明,最后通过实验验证了系统的可用性.

  5. Cross-correlation analysis of the AE index and the interplanetary magnetic field Bz component.

    Science.gov (United States)

    Meng, C.-I.; Tsurutani, B.; Kawasaki, K.; Akasofu, S.-I.

    1973-01-01

    A cross-correlation study between magnetospheric activity (the AE index) and the southward-directed component of the interplanetary magnetic field (IMF) is made for a total of 792 hours (33 days) with a time resolution of about 5.5 min. The peak correlation tends to occur when the interplanetary data are shifted approximately 40 min later with respect to the AE index data. Cross-correlation analysis is conducted on some idealized wave forms to illustrate that this delay between southward turning of the IMF and the AE index should not be interpreted as being the duration of the growth phase.

  6. Mass-loss induced instabilities in fast rotating stars

    CERN Document Server

    Lignières, F; Mangeney, A

    2000-01-01

    To explain the origin of Herbig Ae/Be stars activity, it has been recently proposed that strong mass-losses trigger rotational instabilities in the envelope of fast rotating stars. The kinetic energy transferred to turbulent motions would then be the energy source of the active phenomena observed in the outer atmosphere of Herbig Ae/Be stars (Vigneron et al. 1990; Lignieres et al. 1996). In this paper, we present a one-dimensional model of angular momentum transport which allows to estimate the degree of differential rotation induced by mass-loss. Gradients of angular velocity are very close to - 2 Ømega / R mass-loss, this process occurs in a short time scale as compared to other processes of angular momentum transport. Application of existing stability criteria indicates that rotational instabilities should develop for fast rotating star. Thus, in fast rotating stars with strong winds, shear instabilities are expected to develop and to generate subphotospheric turbulent motions. Albeit very simple, this mo...

  7. Stars Underground

    CERN Multimedia

    Jean Leyder

    1996-01-01

    An imaginary voyage in time where we were witness of the birth of the universe itself, the time of the Big-Bang 15 billion years ago. Particules from the very first moments of time : protons, neutrons and electrons, and also much more energetic one. These particules are preparing to interact collider and generating others which will be the birth to the stars ........

  8. Pulsating stars

    CERN Document Server

    Catelan, M?rcio

    2014-01-01

    The most recent and comprehensive book on pulsating stars which ties the observations to our present understanding of stellar pulsation and evolution theory.  Written by experienced researchers and authors in the field, this book includes the latest observational results and is valuable reading for astronomers, graduate students, nuclear physicists and high energy physicists.

  9. STAR Highlights

    OpenAIRE

    Masui, Hiroshi; collaboration, for the STAR

    2011-01-01

    We report selected results from STAR collaboration at RHIC, focusing on jet-hadron and jet-like correlations, quarkonium suppression and collectivity, di-electron spectrum in both p+p and Au+Au, and higher moments of net-protons as well as azimuthal anisotropy from RHIC Beam Energy Scan program.

  10. 19 CFR 4.76 - Procedures and responsibilities of carriers filing outbound vessel manifest information via the AES.

    Science.gov (United States)

    2010-04-01

    ... outbound vessel manifest information via the AES. 4.76 Section 4.76 Customs Duties U.S. CUSTOMS AND BORDER... manifest information via the AES. (a) The sea carrier's module. The Sea Carrier's Module is a component of... information will be transmitted to Customs via AES for each shipment as far in advance of departure...

  11. Detection of multiple AE signal by triaxial hodogram analysis; Sanjiku hodogram ho ni yoru taju acoustic emission no kenshutsu

    Energy Technology Data Exchange (ETDEWEB)

    Nagano, K.; Yamashita, T. [Muroran Institute of Technology, Hokkaido (Japan)

    1997-05-27

    In order to evaluate dynamic behavior of underground cracks, analysis and detection were attempted on multiple acoustic emission (AE) events. The multiple AE is a phenomenon in which multiple AE signals generated by underground cracks developed in an extremely short time interval are superimposed, and observed as one AE event. The multiple AE signal consists of two AE signals, whereas the second P-wave is supposed to have been inputted before the first S-wave is inputted. The first P-wave is inputted first, where linear three-dimensional particle movements are observed, but the movements are made random due to scattering and sensor characteristics. When the second P-wave is inputted, the linear particle movements are observed again, but are superimposed with the existing input signals and become multiple AE, which creates poor S/N ratio. The multiple AE detection determines it a multiple AE event when three conditions are met, i. e. a condition of equivalent time interval of a maximum value in a scalogram analysis, a condition of P-wave vibrating direction, and a condition of the linear particle movement. Seventy AE signals observed in the Kakkonda geothermal field were analyzed and AE signals that satisfy the multiple AE were detected. However, further development is required on an analysis method with high resolution for the time. 4 refs., 4 figs.

  12. The prediction of AE, ap, and Dst at time lags between 0 and 30 hours

    Science.gov (United States)

    Smart, D. F.; Garrett, H. B.; Shea, M. A.

    1979-01-01

    The magnetic activity indexes AE, ap, and Dst are correlated with approximately 35,000 hours of interplanetary plasma and magnetic field measurements acquired near the Earth (assembled by NASA/NSSDC into a composite data sat). Lag times between the indexes and solar wind parameters ranged from 0 to 30 hours. Correlations at lags less than 6 hours yield results in agreement with previous studies. At greater lags, the correlation coefficients between the solar wind parameters and AE and ap approach these parameters' autocorrelation (persistence) values. For Dst the correlation with solar wind parameters is lower than that with AE and ap in the 3 to 4 hour lag range whereas the autocorrelation of Dst is significantly higher over the entire 0 to 30 hour lag range. The implications of these differences between AE, ap, and Dst are discussed in terms of persistence of solar wind structure.

  13. Auroral Electrojet (AE, AL, AO, AU) - A Global Measure of Auroral Zone Magnetic Activity

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The AE index is derived from geomagnetic variations in the horizontal component observed at selected (10-13) observatories along the auroral zone in the northern...

  14. ?Smart COPVs? - Continued Successful Development of JSC IR&D Acoustic Emissions (AE) SHM Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop and apply promising quantitative pass/fail criteria to CPV using acoustic emission (AE) and lay the foundation for continued development of an automated...

  15. Propagation of Flexural Mode AE Signals in GR/EP Composite Plates

    Science.gov (United States)

    Prosser, W. H.; Gorman, M. R.

    1992-01-01

    It has been documented that AE signals propagate in thin plates as extensional and flexural plate modes. This was demonstrated using simulated AE sources (pencil lead breaks) by Gorman on thin aluminum and gr/ep composite plates and by Gorman and Prosser on thin aluminum plates. A typical signal from a pencil lead break source which identifies these two modes is shown. AE signals from transverse matrix cracking sources in gr/ep composite plates were also shown to propagate as plate modes by Gorman and Ziola. Smith showed that crack growth events in thin aluminum plates under spectrum fatigue loading produced signals that propagated as plate modes. Additionally, Prosser et al. showed that AE signals propagated as plate modes in a thin walled composite tube.

  16. Validation and empirical correction of MODIS AOT and AE over ocean

    Directory of Open Access Journals (Sweden)

    N. A. J. Schutgens

    2013-09-01

    Full Text Available We present a validation study of Collection 5 MODIS level 2 Aqua and Terra AOT (aerosol optical thickness and AE (Ångström exponent over ocean by comparison to coastal and island AERONET (AErosol RObotic NETwork sites for the years 2003–2009. We show that MODIS (MODerate-resolution Imaging Spectroradiometer AOT exhibits significant biases due to wind speed and cloudiness of the observed scene, while MODIS AE, although overall unbiased, exhibits less spatial contrast on global scales than the AERONET observations. The same behaviour can be seen when MODIS AOT is compared against Maritime Aerosol Network (MAN data, suggesting that the spatial coverage of our datasets does not preclude global conclusions. Thus, we develop empirical correction formulae for MODIS AOT and AE that significantly improve agreement of MODIS and AERONET observations. We show these correction formulae to be robust. Finally, we study random errors in the corrected MODIS AOT and AE and show that they mainly depend on AOT itself, although small contributions are present due to wind speed and cloud fraction in AOT random errors and due to AE and cloud fraction in AE random errors. Our analysis yields significantly higher random AOT errors than the official MODIS error estimate (0.03 + 0.05 τ, while random AE errors are smaller than might be expected. This new dataset of bias-corrected MODIS AOT and AE over ocean is intended for aerosol model validation and assimilation studies, but also has consequences as a stand-alone observational product. For instance, the corrected dataset suggests that much less fine mode aerosol is transported across the Pacific and Atlantic oceans.

  17. Incorporation of Wave Pipelined Techniques into Composite S-Box and AES Architectures

    Directory of Open Access Journals (Sweden)

    M. Senthil Kumar

    2014-10-01

    Full Text Available Advanced Encryption Standard is one of the most successful techniques used in various security applications. The AES technique is known to provide reliable security standards, which is why it is preferred over many other methods. The AES architecture consists of S-Box, Shift-Rows, Mix-Columns and Add Round key. Improving the S-Box structure using pipelining improves the speed of operations along with the security. The main aim of this research study is to design a modified composite S-Box for low area, power and high Speed with high security for application in AES process. In this study, we propose a WPT in S-Box also controlling the registers with a clock-gate structure, to further reduce the operational delay and obtain high security. The modified S-Box is then included in the AES architecture with an additional modification on the overall AES architecture by introducing the WPT in every round of AES operation. This is not only improves the speed of operation and also it provides high security compared to many existing techniques along with the area and power reduction. Simulations have been performed in the ModelSim6.3c and Synthesis is carried out using Xilinx10.1.

  18. AE Geomagnetic Index Predictability for High Speed Solar Wind Streams: A Wavelet Decomposition Technique

    Science.gov (United States)

    Guarnieri, Fernando L.; Tsurutani, Bruce T.; Hajra, Rajkumar; Echer, Ezequiel; Gonzalez, Walter D.; Mannucci, Anthony J.

    2014-01-01

    High speed solar wind streams cause geomagnetic activity at Earth. In this study we have applied a wavelet interactive filtering and reconstruction technique on the solar wind magnetic field components and AE index series to allowed us to investigate the relationship between the two. The IMF Bz component was found as the most significant solar wind parameter responsible by the control of the AE activity. Assuming magnetic reconnection associated to southward directed Bz is the main mechanism transferring energy into the magnetosphere, we adjust parameters to forecast the AE index. The adjusted routine is able to forecast AE, based only on the Bz measured at the L1 Lagrangian point. This gives a prediction approximately 30-70 minutes in advance of the actual geomagnetic activity. The correlation coefficient between the observed AE data and the forecasted series reached values higher than 0.90. In some cases the forecast reproduced particularities observed in the signal very well.The high correlation values observed and the high efficacy of the forecasting can be taken as a confirmation that reconnection is the main physical mechanism responsible for the energy transfer during HILDCAAs. The study also shows that the IMF Bz component low frequencies are most important for AE prediction.

  19. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter; Brorsen, Michael

    Nærværende rapport beskriver foreløbige hovedkonklusioner på modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star i perioden 13/9 2004 til 12/11 2004.......Nærværende rapport beskriver foreløbige hovedkonklusioner på modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star i perioden 13/9 2004 til 12/11 2004....

  20. The Old English "Hw(ae)t" and the Old Chinese "Hua,话"——A Look into the Etymology%Hw(ae)t本义

    Institute of Scientific and Technical Information of China (English)

    杜彪

    2007-01-01

    Hw(ae)t为古英语史诗Beowulf的开篇语,此词在现代英语中没有准确的对应词.笔者认为:(1):Hw(ae)t代表着一个很古老的词根,本意为"话";它在印欧语系语言中派生出诸多的疑问代词,英语中几乎所有疑问代词都与之有关;(2)上古汉语中若干个与"说话"有关的词及疑问助词亦与此词根有关;(3)Hw(ae)t代表一种古老的口头文学的开篇形式.Beowulf与中国人口头文学(说书)的开篇形式完全一样,因此,为Hw(ae)t的本义为"话说".

  1. On the infant weight loss of low- to intermediate-mass star clusters

    CERN Document Server

    Weidner, C; Nürnberger, D; Sterzik, M F

    2007-01-01

    Star clusters are born in a highly compact configuration, typically with radii of less than about 1 pc roughly independently of mass. Since the star-formation efficiency is less than 50 per cent by observation and because the residual gas is removed from the embedded cluster, the cluster must expand. In the process of doing so it only retains a fraction f_st of its stars. To date there are no observational constrains for f_st, although Nbody calculations by Kroupa et al. (2001) suggest it to be about 20-30 per cent for Orion-type clusters. Here we use the data compiled by Testi et al. (1997, 1998, 1999) for clusters around young Ae/Be stars and by de Wit et al. (2004, 2005) around young O stars and the study of de Zeeuw et al. (1999) of OB associations and combine these measurements with the expected number of stars in clusters with primary Ae/Be and O stars, respectively, using the empirical correlation between maximal-stellar-mass and star-cluster mass of Weidner & Kroupa (2006). We find that f_st < ...

  2. Planck stars

    CERN Document Server

    Rovelli, Carlo

    2014-01-01

    A star that collapses gravitationally can reach a further stage of its life, where quantum-gravitational pressure counteracts weight. The duration of this stage is very short in the star proper time, yielding a bounce, but extremely long seen from the outside, because of the huge gravitational time dilation. Since the onset of quantum-gravitational effects is governed by energy density --not by size-- the star can be much larger than planckian in this phase. The object emerging at the end of the Hawking evaporation of a black hole can can then be larger than planckian by a factor $(m/m_{\\scriptscriptstyle P})^n$, where $m$ is the mass fallen into the hole, $m_{\\scriptscriptstyle P}$ is the Planck mass, and $n$ is positive. The existence of these objects alleviates the black-hole information paradox. More interestingly, these objects could have astrophysical and cosmological interest: they produce a detectable signal, of quantum gravitational origin, around the $10^{-14} cm$ wavelength.

  3. Hot Gas Lines in T Tauri Stars

    CERN Document Server

    Ardila, David R; Gregory, Scott G; Ingleby, Laura; France, Kevin; Brown, Alexander; Edwards, Suzan; Johns-Krull, Christopher; Linsky, Jeffrey L; Yang, Hao; Valenti, Jeff A; Abgrall, Hervé; Alexander, Richard D; Bergin, Edwin; Bethell, Thomas; Brown, Joanna M; Calvet, Nuria; Espaillat, Catherine; Hillenbrand, Lynne A; Hussain, Gaitee; Roueff, Evelyne; Schindhelm, Eric R; Walter, Frederick M

    2013-01-01

    For Classical T Tauri Stars (CTTSs), the resonance lines of N V, Si IV, and C IV, as well as the He II 1640 A line, act as diagnostics of the accretion process. Here we assemble a large high-resolution dataset of these lines in CTTSs and Weak T Tauri Stars (WTTSs). We present data for 35 stars: one Herbig Ae star, 28 CTTSs, and 6 WTTSs. We decompose the C IV and He II lines into broad and narrow Gaussian components (BC & NC). The most common (50 %) C IV line morphology in CTTSs is that of a low-velocity NC together with a redshifted BC. The velocity centroids of the BCs and NCs are such that V_BC > 4 * V_NC, consistent with the predictions of the accretion shock model, in at most 12 out of 22 CTTSs. We do not find evidence of the post-shock becoming buried in the stellar photosphere due to the pressure of the accretion flow. The He II CTTSs lines are generally symmetric and narrow, less redshifted than the CTTSs C IV lines, by ~10 km/sec. The flux in the BC of the He II line is small compared to that of t...

  4. 基于蒙特卡罗法的FC-AE-ASM网络可靠性研究%Study on reliability of FC-AE-ASM network based on Monte Carlo method

    Institute of Scientific and Technical Information of China (English)

    易川; 翟正军; 羊昌燕

    2014-01-01

    To solve the reliability problem of FC-AE-ASM(Fibre Channel-Avionics Environment-Anonymous Subscriber Messaging)network, based on basic FC-AE-ASM network model, several redundancy structure of the FC-AE-ASM network is introduced. An analysis method of network reliability is proposed. A calculation method of all terminal network reliability and error analysis is developed. Combined with the complexity of the FC-AE-ASM network model that is con-sisted of multiple FC switches, the effect of link redundancy structure, link reliability and node reliability to network reli-ability are analyzed.%对于FC-AE-ASM网络的可靠性问题,从FC-AE-ASM网络的基本模型出发,介绍了两种FC-AE-ASM网络冗余结构;提出了基于蒙特卡罗仿真法的网络可靠性分析方法,给出了FC-AE-ASM网络全端可靠度计算方法,给出了仿真结果的误差分析公式;结合由多个FC交换机组成的复杂FC-AE-ASM网络模型实例,分析链路冗余结构、链路可靠概率和节点可靠概率对FC-AE-ASM网络可靠性的影响。

  5. When stars collide

    NARCIS (Netherlands)

    Glebbeek, E.; Pols, O.R.

    2007-01-01

    When two stars collide and merge they form a new star that can stand out against the background population in a star cluster as a blue straggler. In so called collision runaways many stars can merge and may form a very massive star that eventually forms an intermediate mass blackhole. We have perfor

  6. Measure of the stars

    Energy Technology Data Exchange (ETDEWEB)

    Henbest, N.

    1984-12-13

    The paper concerns the Hertzsprung-Russel (H-R) diagram, which is graph relating the brightness to the surface temperature of the stars. The diagram provides a deep insight into the fundamental properties of the stars. Evolution of the stars; the death of a star; distances; and dating star clusters, are all briefly discussed with reference to the H-R diagram.

  7. Comportamento de Aedes albopictus e de Ae. scapularis adultos (Diptera: Culicidae no Sudeste do Brasil

    Directory of Open Access Journals (Sweden)

    Oswaldo Paulo Forattini

    2000-10-01

    Full Text Available OBJETIVO: Observar e comparar o comportamento das espécies de Aedes albopictus e de Ae. scapularis, na localidade de Pedrinhas, litoral sul do Estado de São Paulo, Brasil. MÉTODOS: As observações foram feitas de outubro de 1996 a janeiro de 2000. Foram realizadas coletas sistemáticas de formas adultas mediante a utilização de isca humana, aspirações ambientais e armadilha tipo Shannon. A domiciliação foi estimada pelo índice de Nuorteva e pela razão de sinantropia. RESULTADOS: Foram feitas 87 coletas diurnas, com a obtenção de 872 adultos fêmeas. As médias de Williams', multiplicadas por 100, foram de 118 e 21 para Ae. albopictus nos horários de 7h às 18h e de 18h às 20h, respectivamente. Quanto a Ae. scapularis, foram de 100 e 106 nos mesmos períodos. Esse último revelou pico de atividade crepuscular vespertina. Na aspiração de abrigos, obteve-se o total de 1.124 espécimens, dos quais 226 Ae. albopictus e 898 Ae. scapularis. O período de janeiro a maio correspondeu ao de maior rendimento para ambos os mosquitos. Quanto à armadilha de Shannon, as coletas realizadas na mata revelaram a ausência de Ae. albopictus. No que concerne à domiciliação, esse último mostrou os maiores valores de índices, enquanto Ae. scapularis revelou comportamento de tipo ubiquista. CONCLUSÕES: Os resultados confirmam outras observações, permitindo levantar hipóteses. Em relação a Ae. scapularis, sugere-se que possa existir fenômeno de diapausa das fêmeas no período verão-outono, a qual cessaria no inverno-primavera quando então a atividade seria retomada. Quanto a Ae. albopictus, os dados sugerem que se trata de população em processo adaptativo ao novo ambiente.

  8. Correlation between Earthquakes and AE Monitoring of Historical Buildings in Seismic Areas

    Directory of Open Access Journals (Sweden)

    Giuseppe Lacidogna

    2015-12-01

    Full Text Available In this contribution a new method for evaluating seismic risk in regional areas based on the acoustic emission (AE technique is proposed. Most earthquakes have precursors, i.e., phenomena of changes in the Earth’s physical-chemical properties that take place prior to an earthquake. Acoustic emissions in materials and earthquakes in the Earth’s crust, despite the fact that they take place on very different scales, are very similar phenomena; both are caused by a release of elastic energy from a source located in a medium. For the AE monitoring, two important constructions of Italian cultural heritage are considered: the chapel of the “Sacred Mountain of Varallo” and the “Asinelli Tower” of Bologna. They were monitored during earthquake sequences in their relative areas. By using the Grassberger-Procaccia algorithm, a statistical method of analysis was developed that detects AEs as earthquake precursors or aftershocks. Under certain conditions it was observed that AEs precede earthquakes. These considerations reinforce the idea that the AE monitoring can be considered an effective tool for earthquake risk evaluation.

  9. Physical parameters of seven field RR Lyrae Stars in Bootes

    CERN Document Server

    Peña, J H; Miller, R Peña; Sareyan, J P; Alvarez, M

    2009-01-01

    Str\\"omgren uvby-beta photometry is reported for the RR Lyrae stars AE, RS, ST, TV, TW, UU, and XX in Bootes. The physical parameters M/Mo, log (L/Lo), M_V, log T_eff and [Fe/H], have been estimated from the Fourier decomposition of the light curves and the empirical calibrations developed for this type of stars. Detailed behavior of the stars along the cycle of pulsation has been determined from the observed photometric indices and the synthetic indices from atmospheric models. The reddening of the zone is found to be negligible, as estimated from the reddening of several objects in the same region of the sky. Hence the distances to the individual objects are also estimated.

  10. Integrated interpretation of AE clusters and fracture system in Hijiori HDR artificial reservoir; Hijiori koon gantai jinko choryuso no AE cluster to kiretsu system ni kansuru togoteki kaishaku

    Energy Technology Data Exchange (ETDEWEB)

    Tezuka, K. [Japan Petroleum Exploration Corp., Tokyo (Japan); Niitsuma, H. [Tohoku University, Sendai (Japan)

    1997-05-27

    With regard to a fracture system in the Hijiori hot dry rock artificial reservoir, an attempt was made on an interpretation which integrates different data. Major factors that characterize development and performance of an artificial reservoir are composed of a fracture system in rocks, which acts as circulating water paths, a heat exchange face and a reservoir space. The system relates not only with crack density distribution, but also with cracks activated by water pressure fracturing, cracks generating acoustic emission (AE), and cracks working as major flow paths, all of which are characterized by having respective behaviors and roles. Characteristics are shown on AE cluster distribution, crack distribution, production zone and estimated stress fields. Mutual relationship among these elements was discussed based on the Coulomb`s theory. The most important paths are characterized by distribution of slippery cracks. Directions and appearance frequencies of the slippery cracks affect strongly directionality of the paths, which are governed by distribution of the cracks (weak face) and stress field. Among the slippery cracks, cracks that generate AE are cracks that release large energy when a slip occurs. Evaluation on slippery crack distribution is important. 7 refs., 8 figs.

  11. Evolution of microstructure and hardness of AE42 alloy after heat treatments

    DEFF Research Database (Denmark)

    Huang, Y.D.; Dieringa, H.; Hort, N.;

    2008-01-01

    The AE42 magnesium alloy was developed for high pressure die casting (HPDC) from low-aluminum magnesium alloys. In this alloy the rare earth (RE) elements were shown to increase creep resistance by forming AlxREy intermetallics along the grain boundaries. The present work investigates...... the microstructure of squeeze cast AE42 magnesium alloy and evaluates its hardness before and after heat treatments. The change in hardness is discussed based on the microstructural observations. Some suggestions are given concerning future design of alloy compositions in order to improve high temperature creep...... properties even further. It is shown that the microstructure of the squeeze-cast AE42 alloy is stable at high temperature 450 degrees C. The subsequent solution and ageing treatments have a limited effect on the hardness. The weak age-hardening is attributed to the precipitation of small amount Of Mg17Al12...

  12. The use of MP-AES for analysis major and micronutrients in soils

    Science.gov (United States)

    Tonutare, Tonu; Rodima, Ako; Künnapas, Allan; Kõlli, Raimo; Albre, Imbi

    2016-04-01

    The ICP with OES or MS detectors is today the most common multielement technigues for soil element analysis. Although the micro-plasma has been available for decades, there were no commercially available instruments on the market. The situation changed in 2011 when the Agilent 4100 MP-AES appeared. The use of nitrogen plasma of the MP-AES provides reduction in the operational and maintenance costs compared to ICP and therefore makes it very perspective for soil analysis. The nitrogen microwave excited plasma has diferent properties compared to ICP argon plasma and this cause the specific behaviour of elements during the excitation. Here we present the results and optimal instrumental parameters for determination of soil nutrients (K, Ca, Mg, Fe and Zn) by MP-AES.

  13. Herschel Observations of a Newly Discovered UX Ori Star in the Large Magellanic Cloud

    Science.gov (United States)

    Clayton, Geoffrey

    2010-10-01

    The LMC star, SSTISAGE1C J050756.44--703453.9, was first noticed during a survey of EROS-2 lightcurves for stars with large irregular brightness variations typical of the R Coronae Borealis (RCB) class. However, the visible spectrum showing emission lines including the Balmer and Paschen series as well as many Fe II lines is emphatically not that of an RCB star. This star has all of the characteristics of a typical UX Ori star. It has a spectral type of approximately A2 and has excited an H II region in its vicinity. However, if it is an LMC member, then it is very luminous for a Herbig Ae/Be star. It shows irregular drops in brightness of up to 2 mag, and displays the reddening and ``blueing'' typical of this class of stars. Its spectrum, showing a combination of emission and absorption lines, is typical of a UX Ori star that is in a decline caused by obscuration from the circumstellar dust. SSTISAGE1C J050756.44--703453.9 has a strong IR excess and significant emission is present out to 500 . Monte Carlo radiative transfer modeling of the SED requires that SSTISAGE1C J050756.44--703453.9 has both a dusty disk as well as a large extended diffuse envelope to fit both the mid- and far-IR dust emission. This star is a new member of the UX Ori subclass of the Herbig Ae/Be stars and only the second such star to be discovered in the LMC.

  14. Growth of Sn on Mo(110) studied by AES and STM

    Science.gov (United States)

    Krupski, A.

    2011-07-01

    Scanning tunneling microscopy (STM) and Auger electron spectroscopy (AES) have been used to investigate the growth behavior of ultra-thin Sn films on a Mo(110) surface at room temperature. An analysis of STM and AES measurements indicates that layer-by-layer growth (Frank-van der Merwe mode) for the first two layers of Sn is observed. For submonolayer coverage, tin prefers to nucleate randomly and creates one atom high islands on Mo terraces. In the completed first and second layer, no ordered regions were observed. As the sample is post-annealed to 800 K, the rearrangement of an existing film suggests a Sn-Mo surface alloy formation.

  15. OPTICAL SPECTROSCOPY OF X-RAY-SELECTED YOUNG STARS IN THE CARINA NEBULA

    Energy Technology Data Exchange (ETDEWEB)

    Vaidya, Kaushar [Physics Department, Birla Institute of Technology and Science Pilani, Pilani 333031, Rajasthan (India); Chen, Wen-Ping; Lee, Hsu-Tai [Graduate Institute of Astronomy, National Central University, 300 Zhongda Road, Zhongli 32001, Taiwan (China)

    2015-12-15

    We present low-resolution optical spectra for 29 X-ray sources identified as either massive star candidates or low-mass pre-main-sequence (PMS) star candidates in the clusters Trumpler 16 and Trumpler 14 of the Carina Nebula. Spectra of two more objects (one with an X-ray counterpart, and one with no X-ray counterpart), not originally our targets, but found close (∼3″) to two of our targets, are presented as well. Twenty early-type stars, including an O8 star, seven B1–B2 stars, two B3 stars, a B5 star, and nine emission-line stars, are identified. Eleven T Tauri stars, including eight classical T Tauri stars (CTTSs) and three weak-lined T Tauri stars, are identified. The early-type stars in our sample are more reddened compared to the previously known OB stars of the region. The Chandra hardness ratios of our T Tauri stars are found to be consistent with the Chandra hardness ratios of T Tauri stars of the Orion Nebula Cluster. Most early-type stars are found to be nonvariable in X-ray emission, except the B2 star J104518.81–594217.9, the B3 star J104507.84–594134.0, and the Ae star J104424.76–594555.0, which are possible X-ray variables. J104452.20–594155.1, a CTTS, is among the brightest and the hardest X-ray sources in our sample, appears to be a variable, and shows a strong X-ray flare. The mean optical and near-infrared photometric variability in the V and K{sub s} bands, of all sources, is found to be ∼0.04 and 0.05 mag, respectively. The T Tauri stars show significantly larger mean variation, ∼0.1 mag, in the K{sub s} band. The addition of one O star and seven B1–B2 stars reported here contributes to an 11% increase of the known OB population in the observed field. The 11 T Tauri stars are the first ever confirmed low-mass PMS stars in the Carina Nebula region.

  16. Can strange stars mimic dark energy stars?

    CERN Document Server

    Deb, Debabrata; Guha, B K; Ray, Saibal

    2016-01-01

    The possibility of strange stars mixed with dark energy to be one of candidates for dark energy stars is the main issue of the present study. Our investigation shows that quark matter is acting as dark energy after certain yet unknown critical condition inside the quark stars. Our proposed model reveals that strange stars mixed with dark energy feature not only a physically acceptable stable model but also mimic characteristics of dark energy stars. The plausible connections are shown through the mass-radius relation as well as the entropy and temperature. We particulary note that two-fluid distribution is the major reason for anisotropic nature of the spherical stellar system.

  17. Lifestyles of the Stars.

    Science.gov (United States)

    National Aeronautics and Space Administration, Cocoa Beach, FL. John F. Kennedy Space Center.

    Some general information on stars is provided in this National Aeronautics and Space Administration pamphlet. Topic areas briefly discussed are: (1) the birth of a star; (2) main sequence stars; (3) red giants; (4) white dwarfs; (5) neutron stars; (6) supernovae; (7) pulsars; and (8) black holes. (JN)

  18. Circumstellar disks around Herbig Be stars

    CERN Document Server

    Alonso-Albi, T; Bachiller, R; Neri, R; Planesas, P; Testi, L; Berne, O; Joblin, C

    2008-01-01

    We have carried out a search for circumstellar disks around Herbig Be stars using the NRAO Very Large Array (VLA) and the IRAM Plateau de Bure (PdB) interferometers. In this Paper, we present our new VLA and PdBI data on the three objects MWC 297, Z CMa and LKHa 215. We have constructed the SED from near-IR to centimeter wavelengths by adding our millimeter and centimeter data to the available data at other wavelengths, mainly Spitzer images. The whole SED has been fitted using a disk+envelope model. In addition, we have compiled all the disk millimeter observations in the literature and made some statistics. We show that the disk mass is usually only a small percentage (less than 10%) of the mass of the whole envelope in HBe stars. Concerning the disks, there are large source to source variations. Two disks of our sample, R Mon and Z CMa, have similar sizes and masses to those found in T Tauri and Herbig Ae stars. The disks around MWC 1080 and MWC 297 are, however, smaller (rout<100 AU). We have not detec...

  19. A Quest for PMS candidate stars at low metallicity: Variable HAe/Be and Be stars in the Small Magellanic Cloud

    CERN Document Server

    De Wit, W J; Lamers, Henny J G L M; Lesquoy, E; Marquette, J B

    2003-01-01

    We report the discovery of 5 new Herbig Ae/Be candidate stars in the Small Magellanic Cloud in addition to the 2 reported in Beaulieu et al. (2001). We discuss these 7 HAeBe candidate stars in terms of (1) their irregular photometric variability, (2) their near infrared emission, (3) their Halpha emission and (4) their spectral type. One star has the typical photometric behaviour that is observed only among Pre-Main Sequence UX Orionis type stars. The objects are more luminous than Galactic HAeBe stars and Large Magellanic Cloud HAeBe candidates of the same spectral type. The stars were discovered in a systematic search for variable stars in a subset of the EROS2 database consisting of 115,612 stars in a field of 24x24 arcmin in the Small Magellanic Cloud. In total we discovered 504 variable stars. After classifying the different objects according to their type of variability, we concentrate on 7 blue objects with irregular photometric behaviour. We cross-identified these objects with emission line catalogues...

  20. Mechanical properties and microstructures of hot extruded AE42 alloy with addition of zinc

    Institute of Scientific and Technical Information of China (English)

    WANG Feng; LIU Zheng; CHEN Li-jia; YU Bao-yi; LIN Li

    2006-01-01

    Mechanical properties and microstructures of AE42 magnesium alloy with addition of Zn and subjected to hot extrusion at 370 ℃ and an extrusion ratio of 8-1 were investigated. The results show that for the AE42 alloy, the addition of Zn can obviously improve its elongation as well as the ultimate tensile and yield strengths below 150 ℃. The addition of Zn can refine the microstructure of the AE42 alloy, and result in the precipitation of Mg17Al12 and MgZn2 phases. Due to the addition of Zn to the AE42 alloy, the amount of Al11RE3 phase decreases, while the Al11RE3 phase becomes short rod-shaped from acicular and block, and distributes along the grain boundaries, which will have a stronger effect on the tensile properties of the alloy at elevated temperature. In addition, with the presence of MgZn2 precipitates, the sliding of grain boundaries is restrained and the strength of the alloy gets enhanced.

  1. Determination of Thorium and Ruthenium in Diuranate by ICP-AES

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Qian-ci; TAO; Miao-miao; LUO; Zhong-yan; ZHAO; Li-fei; HAO; Xiao-juan

    2012-01-01

    <正>Thorium and ruthenium are important impurities that should be monitored in diuranate product. A method for determination of thorium and ruthenium in diuranate was established. Due to the complicated atomic lines of uranium, which have strict interference with that of thorium and ruthenium during determination by ICP-AES, thorium and ruthenium should be separated firstly from uranium matrix before measurement.

  2. MAGIC search for VHE $\\gamma$-ray emission from AE Aquarii in a multiwavelength context

    CERN Document Server

    Aleksić, J; Antonelli, L A; Antoranz, P; Babic, A; Bangale, P; Barrio, J A; González, J Becerra; Bednarek, W; Bernardini, E; Biasuzzi, B; Biland, A; Blanch, O; Bonnefoy, S; Bonnoli, G; Borracci, F; Bretz, T; Carmona, E; Carosi, A; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Caneva, G; De Lotto, B; Wilhelmi, E de Oña; Mendez, C Delgado; Doert, M; Prester, D Dominis; Dorner, D; Doro, M; Einecke, S; Eisenacher, D; Elsaesser, D; Fonseca, M V; Font, L; Frantzen, K; Fruck, C; Galindo, D; López, R J García; Garczarczyk, M; Terrats, D Garrido; Gaug, M; Godinović, N; Muñoz, A González; Gozzini, S R; Hadasch, D; Hanabata, Y; Hayashida, M; Herrera, J; Hildebrand, D; Hose, J; Hrupec, D; Idec, W; Kadenius, V; Kellermann, H; Kodani, K; Konno, Y; Krause, J; Kubo, H; Kushida, J; La Barbera, A; Lelas, D; Lewandowska, N; Lindfors, E; Lombardi, S; López, M; López-Coto, R; López-Oramas, A; Lorenz, E; Lozano, I; Makariev, M; Mallot, K; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martínez, M; Mazin, D; Menzel, U; Miranda, J M; Mirzoyan, R; Moralejo, A; Munar-Adrover, P; Nakajima, D; Niedzwiecki, A; Nilsson, K; Nishijima, K; Noda, K; Nowak, N; Orito, R; Overkemping, A; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, J M; Paredes-Fortuny, X; Persic, M; Moroni, P G Prada; Prandini, E; Preziuso, S; Puljak, I; Reinthal, R; Rhode, W; Ribó, M; Rico, J; Garcia, J Rodriguez; Rügamer, S; Saggion, A; Saito, T; Saito, K; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Spanier, F; Stamatescu, V; Stamerra, A; Steinbring, T; Storz, J; Strzys, M; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Thaele, J; Tibolla, O; Torres, D F; Toyama, T; Treves, A; Uellenbeck, M; Vogler, P; Wagner, R M; Zanin, R; Bogosavljevic, M; Ioannou, Z; Mauche, C W; Palaiologou, E V; Pérez-Torres, M A; Tuominen, T

    2014-01-01

    It has been claimed that the nova-like cataclysmic variable (CV) AE Aquarii (AE Aqr) is a very-high-energy (VHE, $E>$100 GeV) source both on observational and theoretical grounds. We aim to search for VHE gamma-ray emission from AE Aqr during different states of the source at several wavelengths to confirm or rule out previous claims of detection of gamma-ray emission from this object. We report on observations of AE Aqr performed by MAGIC. The source was observed during 12 hours as part of a multiwavelength campaign carried out between May and June 2012 covering the optical, X-ray, and gamma-ray ranges. Besides MAGIC, the other facilities involved were the KVA, Skinakas, and Vidojevica telescopes in the optical and Swift in X-rays. We calculated integral upper limits coincident with different states of the source in the optical. We computed upper limits to the pulsed emission limiting the signal region to 30% of the phaseogram and we also searched for pulsed emission at different frequencies applying the Ray...

  3. Vertical Transmission of Zika Virus by Aedes aegypti and Ae. albopictus Mosquitoes.

    Science.gov (United States)

    Ciota, Alexander T; Bialosuknia, Sean M; Ehrbar, Dylan J; Kramer, Laura D

    2017-05-15

    To determine the potential role of vertical transmission in Zika virus expansion, we evaluated larval pools of perorally infected Aedes. aegypti and Ae. albopictus adult female mosquitoes; ≈1/84 larvae tested were Zika virus-positive; and rates varied among mosquito populations. Thus, vertical transmission may play a role in Zika virus spread and maintenance.

  4. Infection of adult Aedes aegypti and Ae. albopictus mosquitoes with the entomopathogenic fungus Metarhizium anisopliae

    NARCIS (Netherlands)

    Scholte, E.J.; Takken, W.; Knols, B.G.J.

    2007-01-01

    This study describes a laboratory investigation on the use of the insect-pathogenic fungus Metarhizium anisopliae against adult Aedes aegypti and Ae. albopictus mosquitoes. At a dosage of 1.6 × 1010 conidia/m2, applied on material that served as a mosquito resting site, an average of 87.1 ± 2.65% of

  5. Metal content determination in biodiesel samples by microwave mineralization and ICP-AES

    OpenAIRE

    Molina Mayo, Carlos; Garcia Salgado, Sara; Garcia Casillas, David; Brito Alayón, Andrea; Garcia Rodriguez, Teresa; Jimenez Moreno, Francisco; Quijano Nieto, M. Angeles; Bonilla Simon, M. Milagros

    2010-01-01

    El trabajo comprende la puesta a punto de un método de digestión, mediante calentamiento de microondas, de muestras de biodiesel obtenidas mediante catálisis homogénea de aceites vegetales, para la determinación de 20 elementos mediante ICP-AES.

  6. Analyzing Permutations for AES-like Ciphers: Understanding ShiftRows

    DEFF Research Database (Denmark)

    Beierle, Christof; Jovanovic, Philipp; Lauridsen, Martin Mehl;

    2015-01-01

    Designing block ciphers and hash functions in a manner that resemble the AES in many aspects has been very popular since Rijndael was adopted as the Advanced Encryption Standard. However, in sharp contrast to the MixColumns operation, the security implications of the way the state is permuted by ...

  7. Output characteristics of a thin-film piezoelectric AE sensor for magnetic head-disk interaction

    NARCIS (Netherlands)

    Imai, S.; Burger, G.J.; Lammerink, T.S.J.; Fluitman, J.H.J.

    1997-01-01

    A new type of acoustic emission (AE) sensor was developed for detecting head disk interaction in magnetic disk devices. In order to develop a small sensor, we used a thin-film piezoelectric material and mounted it on the Si slider using micromachining techniques. We conducted a basic experiment and

  8. Output characteristics of a thin-film piezoelectric AE sensor for magnetic head-disk interaction

    NARCIS (Netherlands)

    Imai, Satomitsu; Burger, Gert-Jan; Lammerink, Theo S.J.; Fluitman, Jan H.J.

    1996-01-01

    A new type of acoustic emission (AE) sensor was developed for detecting head-disk interaction in magnetic disk devices. In order to develop a small sensor, we used a thin-film piezoelectric material and mounted it on the Si slider using micromachining techniques. We conducted a basic experiment and

  9. Energy-efficient and security-optimized AES hardware design for ubiquitous computing

    Institute of Scientific and Technical Information of China (English)

    Chen Yicheng; Zou Xuecheng; Liu Zhenglin; Han Yu; Zheng Zhaoxia

    2008-01-01

    Ubiquitous computing must incorporate a certain level of security.For the severely resource con-strained applications,the energy-efficient and small size cryptography algorithm implementation is a critical problem.Hardware implementations of the advanced encryption standard(AES)for authentication and encryption are presented.An energy consumption variable is derived to evaluate low-power design strategies for battery-powered devices.It proves that compact AES architectures fail to optimize the AES hardware energy,whereas reducing invalid switching activities and implementing power-optimized sub-modules are the reasonable methods.Implemen tations of different substitution box(S-Boxes)structures are presented with 0.25 μm 1.8 V CMOS(complementary metal oxide semiconductor)standard cell library.The comparisons and trade-offs among area,security,and power are explored.The experimental results show that Galois field composite S-Boxes have smaller size and higheat security but consume considerably more power,whereas decoder-switch-encoder S-Boxes have the best power characteristics with disadvantages in terms of size and security.The combination of these two type S-Boxes instead of homogeneous S-Boxes in AES circuit will lead to optimal schemes.The technique of latch-dividing data path is analyzed,and the quantitative simulation results demonstrate that this approach diminishes the glitches effectively at a very low hardware cost.

  10. Estimating the Willingness to Pay for the Benefit of AES Using the Contingent Valuation Method

    NARCIS (Netherlands)

    Haile, D.T.; Slangen, L.H.G.

    2009-01-01

    This paper presents results of a contingent valuation study based on responses from household members living in Winterswijk, The Netherlands. The respondents are asked to report their preferences on a range of willingness to pay (WTP) for agri-environmental schemes (AES) provided by farmers. Estimat

  11. Investigation of Participation in Adult Education in Turkey: AES Data Analysis

    Science.gov (United States)

    Dincer, N. Nergiz; Tekin-Koru, Ayca; Askar, Petek

    2016-01-01

    The aim of this study is to identify the determinants of participation in adult education in Turkey. The analysis is conducted using the Adult Education Survey (AES), conducted by TurkStat. The results indicate that economic growth in the sector of employment significantly and positively affects the odds for adult education participation. The data…

  12. Data of evolutionary structure change: 1A2AE-2NOTA [Confc[Archive

    Lifescience Database Archive (English)

    Full Text Available 1A2AE-2NOTA 1A2A 2NOT E A NLLQFNKMIKEETG--KNAIPFYAFYGCYCGGGGNGKPK...A 2NOTA KKGCSPKMSAYD 1.309999942779541 tion> 0.1770000010728836 0.842000007...519989 0.7739999890327454 0.8339999914169312 -0.40299999713897705 0.37599998712539673 ...> 2NOT A 2NOTA <

  13. 76 FR 4089 - Proposed Information Collection; Comment Request; Automated Export System (AES) Program

    Science.gov (United States)

    2011-01-24

    ... basis for the official U.S. export trade statistics. These statistics are used to determine the balance... complete and accurate export statistics, as well as strengthening export controls. In spite of new filing... the Bureau of Industry and Security when valued over $2,500 per Schedule B. The AES program is...

  14. Production and Perception of the English /ae/-/?/ Contrast in Switched-Dominance Speakers

    Science.gov (United States)

    Casillas, Joseph V.; Simonet, Miquel

    2016-01-01

    This study investigates how fluent second-language (L2) learners of English produce and perceive the /ae/-/?/ vowel contrast of Southwestern American English. Two learner groups are examined: (1) early, proficient English speakers who were raised by Spanish-speaking families but who became dominant in English during childhood and, as adults, lack…

  15. The anion exchanger Ae2 is required for enamel maturation in mouse teeth

    NARCIS (Netherlands)

    Lyaruu, D.M.; Bronckers, A.L.J.J.; Mulder, L.; Mardones, P.; Medina, J.F.; Kellokumpu, S.; Oude Elferink, R.P.J.; Everts, V.

    2008-01-01

    One of the mechanisms by which epithelial cells regulate intracellular pH is exchanging bicarbonate for Cl-. We tested the hypothesis that in ameloblasts the anion exchanger-2 (Ae2) is involved in pH regulation during maturation stage amelogenesis. Quantitative X-ray microprobe mineral content analy

  16. Distant star clusters of the Milky Way in MOND

    Science.gov (United States)

    Haghi, H.; Baumgardt, H.; Kroupa, P.

    2011-03-01

    We determine the mean velocity dispersion of six Galactic outer halo globular clusters, AM 1, Eridanus, Pal 3, Pal 4, Pal 15, and Arp 2 in the weak acceleration regime to test classical vs. modified Newtonian dynamics (MOND). Owing to the nonlinearity of MOND's Poisson equation, beyond tidal effects, the internal dynamics of clusters is affected by the external field in which they are immersed. For the studied clusters, particle accelerations are much lower than the critical acceleration a0 of MOND, but the motion of stars is neither dominated by internal accelerations (ai ≫ ae) nor external accelerations (ae ≫ ai). We use the N-body code N-MODY in our analysis, which is a particle-mesh-based code with a numerical MOND potential solver developed by Ciotti et al. (2006, ApJ, 640, 741) to derive the line-of-sight velocity dispersion by adding the external field effect. We show that Newtonian dynamics predicts a low-velocity dispersion for each cluster, while in modified Newtonian dynamics the velocity dispersion is much higher. We calculate the minimum number of measured stars necessary to distinguish between Newtonian gravity and MOND with the Kolmogorov-Smirnov test. We also show that for most clusters it is necessary to measure the velocities of between 30 to 80 stars to distinguish between both cases. Therefore the observational measurement of the line-of-sight velocity dispersion of these clusters will provide a test for MOND.

  17. MANAGEMENT OF AE-CB/COPD: A SURVEY OF RESPIRATORY PHYSICIANS IN SOME REGIONS OF CHINA

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Objective To investigate the bacteria spectrum isolated from AE-CB/ COPD and the manner of management of AE-CB/ COPD in respiratory or internal medicine department in some regions of China. Methods Respiratory physicians received questionnaire at randomization just after they managed a patient presenting to outpatient department with AE-CB/ COPD, on general conditions and symptoms of patients, type of examinations, diagnosis, type of antibiotics used and mode of administration. Results of sputum bacteria culture were followed up.Results Among the 1583 AE-CB/COPD , 63. 04% were male and 35. 19% were female. 54.6% of them were older than 60 years. 81.87% of the patients produced sputum. Sputum bacteria culture, chest X-ray and chest CT were carried out to 21.3%, 66. 3% and 11. 1% patients, respectively. 355 strains were isolated from patients whose sputum bacteria culture was positive. Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis were the three most isolates. 84. 7% of the 1583 AE-CB/COPD received 1692 times of antibiotic prescribing. The most frequently prescribed antibiotic were B-lactams (51.36% of all antibiotic prescribing), macrolides (14.01%) and quinolones (31.03%). Much more macrolides were prescribed in the area where more patients pay the medicines at his own expense than those in the area where more patients share public health service.Conclusion In China, respiratory physicians can reasonably select antibiotics to manage acute exacerbation of chronic bronchitis/ chronic obstructive pulmonary disease in pulmonary outpatient department. Sputum culture is done in part of the patients, but susceptibility tests are missing. One issue revealed by the survey is that the list of prescribing medications laid down by government have great influence on antibiotic use.

  18. The Cambridge Double Star Atlas

    Science.gov (United States)

    MacEvoy, Bruce; Tirion, Wil

    2015-12-01

    Preface; What are double stars?; The binary orbit; Double star dynamics; Stellar mass and the binary life cycle; The double star population; Detecting double stars; Double star catalogs; Telescope optics; Preparing to observe; Helpful accessories; Viewing challenges; Next steps; Appendices: target list; Useful formulas; Double star orbits; Double star catalogs; The Greek alphabet.

  19. A Comparison of Van Allen Belt Radiation Environment Modeling Programs: AE8/AP8 Legacy, AE9/AP9, and SPENVIS

    Science.gov (United States)

    Reed, Evan; Pellish, Jonathan

    2016-01-01

    In the space surrounding Earth there exists an active radiation environment consisting mostly of electrons and protons that have been trapped by Earths magnetic field. This radiation, also known as the Van Allen Belts, has the potential to damage man-made satellites in orbit; thus, proper precautions must be taken to shield NASA assets from this phenomenon. Data on the Van Allen Belts has been collected continuously by a multitude of space-based instruments since the beginning of space exploration. Subsequently, using theory to fill in the gaps in the collected data, computer models have been developed that take in the orbital information of a hypothetical mission and output the expected particle fluence and flux for that orbit. However, as new versions of the modeling system are released, users are left wondering how the new version differs from the old. Therefore, we performed a comparison of three different editions of the modeling system: AE8/AP8 (legacy), which is included in the model 9 graphical user interface as an option for ones calculations, AE9/AP9, and the Space Environment Information System (SPENVIS), which is an online-based form of AE8/AP8 developed by NASA and the European Space Agency that changed the code to allow the program to extrapolate data to predict fluence and flux at higher energies. Although this evaluation is still ongoing, it is predicted that the model 8 (legacy) and SPENVIS version will have identical outputs with the exception of the extended energy levels from SPENVIS, while model 9 will provide different fluences than model 8 based on additional magnetic field descriptions and on-orbit data.

  20. 40 CFR 174.530 - Bacillus thuringiensis Cry2Ae protein in cotton; temporary exemption from the requirement of a...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bacillus thuringiensis Cry2Ae protein... REQUIREMENTS FOR PLANT-INCORPORATED PROTECTANTS Tolerances and Tolerance Exemptions § 174.530 Bacillus... Bacillus thuringiensis Cry2Ae protein in or on the food commodities of cotton, cotton; cotton,...

  1. 77 FR 6471 - Bacillus thuringiensis Cry2Ae Protein in Cotton; Exemption from the Requirement of a Tolerance

    Science.gov (United States)

    2012-02-08

    ... AGENCY 40 CFR Part 174 Bacillus thuringiensis Cry2Ae Protein in Cotton; Exemption from the Requirement of... regulation establishes an exemption from the requirement of a tolerance for residues of Bacillus... residues of Bacillus thuringiensis Cry2Ae protein in cotton under the FFDCA. DATES: This regulation...

  2. Production of Mucosally Transmissible SHIV Challenge Stocks from HIV-1 Circulating Recombinant Form 01_AE env Sequences.

    Directory of Open Access Journals (Sweden)

    Lawrence J Tartaglia

    2016-02-01

    Full Text Available Simian-human immunodeficiency virus (SHIV challenge stocks are critical for preclinical testing of vaccines, antibodies, and other interventions aimed to prevent HIV-1. A major unmet need for the field has been the lack of a SHIV challenge stock expressing circulating recombinant form 01_AE (CRF01_AE env sequences. We therefore sought to develop mucosally transmissible SHIV challenge stocks containing HIV-1 CRF01_AE env derived from acutely HIV-1 infected individuals from Thailand. SHIV-AE6, SHIV-AE6RM, and SHIV-AE16 contained env sequences that were >99% identical to the original HIV-1 isolate and did not require in vivo passaging. These viruses exhibited CCR5 tropism and displayed a tier 2 neutralization phenotype. These challenge stocks efficiently infected rhesus monkeys by the intrarectal route, replicated to high levels during acute infection, and established chronic viremia in a subset of animals. SHIV-AE16 was titrated for use in single, high dose as well as repetitive, low dose intrarectal challenge studies. These SHIV challenge stocks should facilitate the preclinical evaluation of vaccines, monoclonal antibodies, and other interventions targeted at preventing HIV-1 CRF01_AE infection.

  3. 75 FR 11169 - AES Sparrows Point LNG, LLC; Mid-Atlantic Express, LLC; Notice of Availability of the Revised...

    Science.gov (United States)

    2010-03-10

    ... Federal Energy Regulatory Commission AES Sparrows Point LNG, LLC; Mid-Atlantic Express, LLC; Notice of... Sparrows Point LNG Terminal and Pipeline Project March 1, 2010. The staff of the Federal Energy Regulatory... operation of a liquefied natural gas (LNG) import terminal and natural gas pipeline proposed by AES...

  4. 75 FR 20591 - AES Sparrows Point LNG, LLC and Mid-Atlantic Express, LLC; Notice of Final General Conformity...

    Science.gov (United States)

    2010-04-20

    ... Energy Regulatory Commission AES Sparrows Point LNG, LLC and Mid-Atlantic Express, LLC; Notice of Final General Conformity Determination for Pennsylvania for the Proposed Sparrows Point LNG Terminal and... liquefied natural gas (LNG) import terminal and natural gas pipeline proposed by AES Sparrows Point LNG,...

  5. [Software development of multi-element transient signal acquisition and processing with multi-channel ICP-AES].

    Science.gov (United States)

    Zhang, Y; Zhuang, Z; Wang, X; Zhu, E; Liu, J

    2000-02-01

    A software for multi-channel ICP-AES multi-element transient signal acquisition and processing were developed in this paper. It has been successfully applied to signal acquisition and processing in many transient introduction techniques on-line hyphenated with multi-channel ICP-AES.

  6. Effects of number of events and relay point density on accuracy of three-dimensional AE-tomography

    NARCIS (Netherlands)

    Kobayashi, Y.; Shiotani, T.; Oda, K.

    2013-01-01

    This paper introduces results of numerical investigations on accuracy of elastic wave velocity distribution in Three-dimensional AE-Tomography. A series of numerical analyses is conducted by changing number of events and density of relay points for the investigation. AE-Tomography is an identificati

  7. CoRoT\\,102699796, the first metal-poor Herbig Ae pulsator: a hybrid $\\delta$ Sct-$\\gamma$ Dor variable?

    CERN Document Server

    Ripepi, V; Di Criscienzo, M; Catanzaro, G; Palla, F; Marconi, M; Ventura, P; Neiner, C; Catala, C; Bernabei, S

    2011-01-01

    We present the analysis of the time series observations of CoRoT\\,102699796 obtained by the CoRoT satellite that show the presence of five independent oscillation frequencies in the range 3.6-5 c/d. Using spectra acquired with FLAMES@VLT, we derive the following stellar parameters: spectral type F1V, T$_{\\rm eff}$=7000$\\pm$200 K, log(g)=$3.8\\pm0.4$, [M/H]=$-1.1\\pm0.2$, $v$sin$i$=$50\\pm5$ km/s, L/L$_{\\odot}$=21$^{+21}_{-11}$. Thus, for the first time we report the existence of a metal poor, intermediate-mass PMS pulsating star. Ground-based and satellite data are used to derive the spectral energy distribution of CoRoT\\,102699796 extending from the optical to mid-infrared wavelengths. The SED shows a significant IR excess at wavelengths greater than $\\sim5 \\mu$. We conclude that CoRoT\\,102699796 is a young Herbig Ae (F1Ve) star with a transitional disk, likely associated to the HII region [FT96]213.1-2.2. The pulsation frequencies have been interpreted in the light of the non-radial pulsation theory, using the...

  8. [Quantitative surface analysis of Pt-Co, Cu-Au and Cu-Ag alloy films by XPS and AES].

    Science.gov (United States)

    Li, Lian-Zhong; Zhuo, Shang-Jun; Shen, Ru-Xiang; Qian, Rong; Gao, Jie

    2013-11-01

    In order to improve the quantitative analysis accuracy of AES, We associated XPS with AES and studied the method to reduce the error of AES quantitative analysis, selected Pt-Co, Cu-Au and Cu-Ag binary alloy thin-films as the samples, used XPS to correct AES quantitative analysis results by changing the auger sensitivity factors to make their quantitative analysis results more similar. Then we verified the accuracy of the quantitative analysis of AES when using the revised sensitivity factors by other samples with different composition ratio, and the results showed that the corrected relative sensitivity factors can reduce the error in quantitative analysis of AES to less than 10%. Peak defining is difficult in the form of the integral spectrum of AES analysis since choosing the starting point and ending point when determining the characteristic auger peak intensity area with great uncertainty, and to make analysis easier, we also processed data in the form of the differential spectrum, made quantitative analysis on the basis of peak to peak height instead of peak area, corrected the relative sensitivity factors, and verified the accuracy of quantitative analysis by the other samples with different composition ratio. The result showed that the analytical error in quantitative analysis of AES reduced to less than 9%. It showed that the accuracy of AES quantitative analysis can be highly improved by the way of associating XPS with AES to correct the auger sensitivity factors since the matrix effects are taken into account. Good consistency was presented, proving the feasibility of this method.

  9. 英语写作 AES 系统评分效度的实证研究%An empirical research into scoring validity of AES

    Institute of Scientific and Technical Information of China (English)

    王海军

    2016-01-01

    英语写作自动评分系统( AES)在国外的英语写作测试和教学领域应用越来越广泛,但国内对其信、效度的实证研究还十分欠缺。以句酷网为例,从人分散度、相关性和等级一致性等方面研究了AES系统的评分效度。结果表明,尽管机器评分区分度不如人工评分,但其总的评分效度尚可,其结果的稳定性可以满足国内英语写作课堂教学的需要。%Although AES is playing a more and more important part in English writing tests and teaching abroad , little empirical research has been carried out into its reliability and validity in Chi-na.The research, a case study of Juku AES , investigated its scoring validity from the perspectives of person separability , consistency and classification agreement .It is concluded that the scoring va-lidity of Juku is so adequate as to satisfy the needs of English classroom writing tasks in spite of its relatively poorer discrimination .

  10. Variability of Disk Emission in Pre-main Sequence and Related Stars. V. Changes in the Innermost Disk Structure of the Herbig AE Star HD 31648 = MWC 480

    Science.gov (United States)

    Fernandes, Rachel; Long, Zachary; Sitko, Michael L.; Grady, C. A.; Kusakabe, Nobuhiko

    2017-01-01

    We present five epochs of near IR observations of the protoplanetary disk around HD 31648 (MWC 480). A mass accretion rate of approximately 1.1×10-7 Msun/year was derived from Brγ and Paβ lines. The spectral energy distribution (SED) reveals a variability of about 30% between 1.5 and 10 microns. We present the theoretical modeling analysis of the disk in HD 31648 using Monte-Carlo Radiation Transfer Code (MRTC). We find that varying the height of the inner rim successfully produces a shift in the NIR flux.

  11. Molecular evolution of HIV-1 CRF01_AE Env in Thai patients.

    Directory of Open Access Journals (Sweden)

    Samatchaya Boonchawalit

    Full Text Available BACKGROUND: The envelope glycoproteins (Env, gp120 and gp41, are the most variable proteins of human immunodeficiency virus type 1 (HIV-1, and are the major targets of humoral immune responses against HIV-1. A circulating recombinant form of HIV-1, CRF01_AE, is prevalent throughout Southeast Asia; however, only limited information regarding the immunological characteristics of CRF01_AE Env is currently available. In this study, we attempted to examine the evolutionary pattern of CRF01_AE Env under the selection pressure of host immune responses. METHODOLOGY/PRINCIPAL FINDINGS: Peripheral blood samples were collected periodically over 3 years from 15 HIV-1-infected individuals residing in northern Thailand, and amplified env genes from the samples were subjected to computational analysis. The V5 region of gp120 showed highest variability in several samples over 3 years, whereas the V1/V2 and/or V4 regions of gp120 also showed high variability in many samples. In addition, the N-terminal part of the C3 region of gp120 showed highest amino acid diversity among the conserved regions of gp120. Chronological changes in the numbers of amino acid residues in gp120 variable regions and potential N-linked glycosylation (PNLG sites are involved in increasing the variability of Env gp120. Furthermore, the C3 region contained several amino acid residues potentially under positive selection, and APOBEC3 family protein-mediated G to A mutations were frequently detected in such residues. CONCLUSIONS/SIGNIFICANCE: Several factors, including amino acid substitutions particularly in gp120 C3 and V5 regions as well as changes in the number of PNLG sites and in the length of gp120 variable regions, were revealed to be involved in the molecular evolution of CRF01_AE Env. In addition, a similar tendency was observed between CRF01_AE and subtype C Env with regard to the amino acid variation of gp120 V3 and C3 regions. These results may provide important information for

  12. Potential topical natural repellent against Ae. aegypti, Culex sp. and Anopheles sp. mosquitoes

    Directory of Open Access Journals (Sweden)

    Dewi Nur Hodijah

    2014-08-01

    Full Text Available AbstrakLatar belakang:Minyak atsiri daun sirih diketahui mempunyai daya proteksi. Dibuatkan losion berdasarkan pengantar sediaan farmasi yang ditambahkan minyak atsiri daun nilam. Sediaan losion dipilih agar dapat menempel lebih lama di permukaan kulit. Tujuan penelitian ini untuk membandingkan daya proteksi antara losion dengan penambahan minyak nilam dan losion tanpa penambahan minyak nilam dibandingkan daya proteksi dengan DEET. Metode: Penelitian ini merupakan penelitian eksperimental laboratorium. Semua nyamuk uji berasal dari insektarium laboratorium penelitian kesehatan Loka litbang P2B2 Ciamis. Konsentrasi minyak atsiri daun sirih dalam losion adalah 4%; konsentrasi minyak nilam sebagai zat pengikat adalah 0,4%. Formula yang digunakan yaitu formula dasar yang ada pada pengantar sediaan farmasi. Uji repelensi dilakukan dengan menggunakan metoda yang direkomendasikan oleh Komisi pestisida.Hasil: Dihasilkan formulasi losion yang stabil dan masih memenuhi standar formulasi sediaan. Berdasarkan hasil, diperoleh data bahwa DEET dan losion hasil modifikasi memiliki rata-rata daya proteksi di atas 90% selama 6 jam terhadap nyamuk Ae.aegypti dan Culex sp. Kesimpulan: Penambahan minyak nilam pada losion sirih dapat meningkatkan daya proteksi terhadap hinggapan nyamuk Ae. aegypti dan Culex sp. (Health Science Indones 2014;1:44-8Kata kunci:repelen alamiah, minyak atsiri, daun sirih, daun nilam, Ae. aegypti, Culex sp.AbstractBackground: Betel leaf essential oil lotion has been known to have insect repellent properties. A lotion was made based on a pharmaceutical formula from a monograph where patchouli leaf essential oil was added. A lotion preparation was intended to enhance adherence of the formula on the surface of the skin. The purpose of this study was to compare protection percentage of lotion with patchouli oil and without patchouli oil lotion compared to DEET.Methods: This study is an experimental laboratory-based research. All mosquitoes

  13. Photometric activity of UX orionis stars and related objects in the near infrared and optical: CO Ori, RR Tau, UX Ori, and VV Ser

    Science.gov (United States)

    Shenavrin, V. I.; Rostopchina-Shakhovskaya, A. N.; Grinin, V. P.; Demidova, T. V.; Shakhovskoi, D. N.; Belan, S. P.

    2016-08-01

    This paper continues a study of the photometric activity of UX Ori stars in the optical and near-infrared ( JHKLM bands) initiated in 2000. For comparison, the list of program stars contains two Herbig Ae stars that are photometrically quiet in the optical: MWC480 andHD179218. Fadings ofUXOri stars in the optical ( V band) due to sporadic increases of the circumstellar extinction are also observed in the infrared (IR), but with decreasing amplitude. Two stars, RR Tau and UX Ori, displayed photometric events when V -band fadings were accompanied by an increase in IR fluxes. Among the two Herbig Ae stars that are photometrically quiet in the optical, MWC 480 proved to be fairly active in the IR. Unlike the UX Ori stars, the variation amplitude of MWC 480 increases from the J band to the M band. In the course of the observations, no deep fadings in the IR bands were detected. This indicates that eclipses of the program stars have a local nature, and are due to extinction variations in the innermost regions of the circumstellar disks. The results presented testify to an important role of the alignment of the circumstellar disks relative to the direction towards the observer in determining the observed IR variability of young stars.

  14. ENERGY STAR Certified Furnaces

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 4.0 ENERGY STAR Program Requirements for Furnaces that are effective as of February 1,...

  15. ENERGY STAR Certified Boilers

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 3.0 ENERGY STAR Program Requirements for Boilers that are effective as of October 1,...

  16. ENERGY STAR Certified Computers

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 6.1 ENERGY STAR Program Requirements for Computers that are effective as of June 2, 2014....

  17. Modified Redundancy based Technique—a New Approach to Combat Error Propagation Effect of AES

    Science.gov (United States)

    Sarkar, B.; Bhunia, C. T.; Maulik, U.

    2012-06-01

    Advanced encryption standard (AES) is a great research challenge. It has been developed to replace the data encryption standard (DES). AES suffers from a major limitation of error propagation effect. To tackle this limitation, two methods are available. One is redundancy based technique and the other one is bite based parity technique. The first one has a significant advantage of correcting any error on definite term over the second one but at the cost of higher level of overhead and hence lowering the processing speed. In this paper, a new approach based on the redundancy based technique is proposed that would certainly speed up the process of reliable encryption and hence the secured communication.

  18. An up-to-date instrumentation system for detection, location and characterization of AE signals

    Science.gov (United States)

    Belcredi, D.; Sala, A.; Tornelli, C.

    1988-11-01

    An acoustic emission data overseeing system (AEDOS) has been developed for detection, location, and multiparametrical analysis of AE events such as amplitude, rise time, duration, energy, and delay time. The equipment comprises three main sections: the 'in field part' to detect and condition the AE events; the 'front end' that collects all the signals, makes the first screening among the signals, and measures the main parameters of the events; and the 'computer' to set up the system, to store the data, to analyze and display parametric isthograms, graphics, and location maps, and to supply an easy menu driven interface to the operator. A detailed functional description including performance specification of the system is given.

  19. On using peak amplitude and rise time for AE source characterization

    Indian Academy of Sciences (India)

    M A Majeed; C R L Murthy

    2002-06-01

    Acoustic Emission (AE) signals, which are electrical version of acoustic emissions, are usually analysed using a set of signal parameters. The major objective of signal analysis is to study the characteristics of the sources of emissions. Peak amplitude $(P_a)$ and rise time $(R_t)$ are two such parameters used for source characterization. In this paper, we theoretically investigate the efficiency of $P_a$ and $R_t$ to classify and characterize AE sources by modelling the input stress pulse and transducer. Analytical expressions obtained for $P_a$ and $R_t$ clearly indicate their use and efficiency for source characterization. It is believed that these results may be of use to investigators in areas like control systems and signal processing also.

  20. A SOPC-BASED Evaluation of AES for 2.4 GHz Wireless Network

    Science.gov (United States)

    Ken, Cai; Xiaoying, Liang

    In modern systems, data security is needed more than ever before and many cryptographic algorithms are utilized for security services. Wireless Sensor Networks (WSN) is an example of such technologies. In this paper an innovative SOPC-based approach for the security services evaluation in WSN is proposed that addresses the issues of scalability, flexible performance, and silicon efficiency for the hardware acceleration of encryption system. The design includes a Nios II processor together with custom designed modules for the Advanced Encryption Standard (AES) which has become the default choice for various security services in numerous applications. The objective of this mechanism is to present an efficient hardware realization of AES using very high speed integrated circuit hardware description language (Verilog HDL) and expand the usability for various applications. As compared to traditional customize processor design, the mechanism provides a very broad range of cost/performance points.

  1. FPGA Implementation of an Area Optimized Architecture for 128 bit AES Algorithm

    Directory of Open Access Journals (Sweden)

    S Ramanathan

    2016-05-01

    Full Text Available This paper aims at FPGA Implementation of an Area Optimized Architecture for 128 bit AES Algorithm. The conventional designs use a separate module for 32 bit byte substitution and 128 bit byte substitution. The 32 bit byte substitution is used in round key generation and the 128 bit byte substitution is used in the rounds. This report presents a modified architecture of 128 bit byte substitution module using a single 32 bit byte substitution module to reduce area.The AES encryption and decryption algorithm were designed using Verilog HDL. The functionality of the modules were checked using ModelSim. The simulations were carried out in ModelSim and Quartus II. The algorithm was implemented in FPGA and achieved a 2% reduction in the total logic element utilization

  2. Comparison of low-temperature oxides on polycrystalline InP by AES, SIMS and XPS

    Science.gov (United States)

    Kazmerski, L. L.; Ireland, P. J.; Sheldon, P.; Chu, T. L.; Chu, S. S.; Lin, C. L.

    1980-10-01

    Oxides and their interfaces with polycrystalline InP are examined using complementary high-resolution AES, SIMS and XPS. The oxides, grown by low-temperature dry and wet processes, are compared for composition and phase content. SIMS and AES depth-composition data are used to compare the uniformity of the oxide layers and the composition of the interfacial region. Confirmation of impurity accumulation at the oxide-InP interfaces is presented, including buildup of elemental P and InP dopant, S. Other impurities associated with the growth of the wet oxide are found to be localized at the interface. Some evidence of impurity accumulation at grain boundaries at the wet oxide-polycrystalline InP interface is provided by SIMS and EBIC.

  3. Research on tensile fracture process of ring-spun yarn based on AE technique and HHT

    Directory of Open Access Journals (Sweden)

    Yajing XUE

    Full Text Available The audio signals of polyester filament and ring-spun yarn were collected respectively during tensile failure by self-built Acoustic Emission detection system (AE for short, which is based on the conventional yarn tensile strength tester. And then the Hilbert Huang transform (HHT program was compiled by Matlab software to analysis and process the collected signals, in order to get the time-frequency characteristics of each damage source in the yarn tensile fracture process. The results show that, AE signal via HHT can be identified two modes involved in polyester ring-spun yarn tensile fracture process, which are fiber fracture and fiber slippage. And the characteristic frequencies of the modes are 30, 20 kHz and 6, 3 kHz respectively. Thus, this paper provides an effective new approach for the analysis and further research of yarn tensile fracture mechanism.

  4. Fracturing tests on reservoir rocks: Analysis of AE events and radial strain evolution

    CERN Document Server

    Pradhan, S; Fjær, E; Stenebråten, J; Lund, H K; Sønstebø, E F; Roy, S

    2015-01-01

    Fracturing in reservoir rocks is an important issue for the petroleum industry - as productivity can be enhanced by a controlled fracturing operation. Fracturing also has a big impact on CO2 storage, geothermal installation and gas production at and from the reservoir rocks. Therefore, understanding the fracturing behavior of different types of reservoir rocks is a basic need for planning field operations towards these activities. In our study, the fracturing of rock sample is monitored by Acoustic Emission (AE) and post-experiment Computer Tomography (CT) scans. The fracturing experiments have been performed on hollow cylinder cores of different rocks - sandstones and chalks. Our analysis show that the amplitudes and energies of acoustic events clearly indicate initiation and propagation of the main fractures. The amplitudes of AE events follow an exponential distribution while the energies follow a power law distribution. Time-evolution of the radial strain measured in the fracturing-test will later be comp...

  5. On the Rapid Spin-down and Low Luminosity Pulsed Emission from AE Aquarii

    CERN Document Server

    Choi, C S; Choi, Chul-Sung; Yi, Insu

    1999-01-01

    AE Aqr is an unusual close binary system with a very short white dwarf spin period, a high spin-down rate, a relatively low quiescent luminosity, and clear pulse signals. The exact nature of the large spin-down power has not been well explained mainly due to the fact that the observed luminosities in various energy ranges are much lower than the spin-down power. We consider an unconventional picture of AE Aqr in which an accreting white dwarf, modeled as a magnetic dipole whose axis is misaligned with the spin axis, is rapidly spun-down via gravitational radiation emission and therefore the spin-down power is not directly connected to any observable electromagnetic emission.

  6. Autonomous Star Tracker Algorithms

    DEFF Research Database (Denmark)

    Betto, Maurizio; Jørgensen, John Leif; Kilsgaard, Søren

    1998-01-01

    Proposal, in response to an ESA R.f.P., to design algorithms for autonomous star tracker operations.The proposal also included the development of a star tracker breadboard to test the algorithms performances.......Proposal, in response to an ESA R.f.P., to design algorithms for autonomous star tracker operations.The proposal also included the development of a star tracker breadboard to test the algorithms performances....

  7. Star operations and Pullbacks

    OpenAIRE

    Fontana, Marco; Park, Mi Hee

    2003-01-01

    In this paper we study the star operations on a pullback of integral domains. In particular, we characterize the star operations of a domain arising from a pullback of ``a general type'' by introducing new techniques for ``projecting'' and ``lifting'' star operations under surjective homomorphisms of integral domains. We study the transfer in a pullback (or with respect to a surjective homomorphism) of some relevant classes or distinguished properties of star operations such as $v-, t-, w-, b...

  8. Validation of the French version of the Acceptability E-scale (AES) for mental E-health systems.

    Science.gov (United States)

    Micoulaud-Franchi, Jean-Arthur; Sauteraud, Alain; Olive, Jérôme; Sagaspe, Patricia; Bioulac, Stéphanie; Philip, Pierre

    2016-03-30

    Despite the increasing use of E-health systems for mental-health organizations, there is a lack of psychometric tools to evaluate their acceptability by patients with mental disorders. Thus, this study aimed to translate and validate a French version of the Acceptability E-scale (AES), a 6-item self-reported questionnaire that evaluates the extent to which patients find E-health systems acceptable. A forward-backward translation of the AES was performed. The psychometric properties of the French AES version, with construct validity, internal structural validity and external validity (Pearson's coefficient between AES scores and depression symptoms on the Beck Depression Inventory II) were analyzed. In a sample of 178 patients (mean age=46.51 years, SD=12.91 years), the validation process revealed satisfactory psychometric properties: factor analysis revealed two factors: "Satisfaction" (3 items) and "Usability" (3 items) and Cronbach's alpha was 0.7. No significant relation was found between AES scores and depression symptoms. The French version of the AES revealed a two-factor scale that differs from the original version. In line with the importance of acceptability in mental health and with a view to E-health systems for patients with mental disorders, the use of the AES in psychiatry may provide important information on acceptability (i.e., satisfaction and usability).

  9. Integrated Design for Marketing and Manufacturing team: An examination of LA-ICP-AES in a mobile configuration. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1994-05-01

    The Department of Energy (DOE) has identified the need for field-deployable elemental analysis devices that are safer, faster, and less expensive than the fixed laboratory procedures now used to screen hazardous waste sites. As a response to this need, the Technology Integration Program (TIP) created a mobile, field-deployable laser ablation-inductively coupled plasma-atomic emission spectrometry (LA-ICP-AES) sampling and analysis prototype. Although the elemental. screening prototype has been successfully field-tested, continued marketing and technical development efforts are required to transfer LA-ICP-AES technology to the commercial sector. TIP established and supported a student research and design group called the Integrated Design for Marketing and Manufacturing (IDMM) team to advance the technology transfer of mobile, field-deployable LA-ICP-AES. The IDMM team developed a conceptual design (which is detailed in this report) for a mobile, field-deployable LA-ICP-AES sampling and analysis system, and reports the following findings: Mobile, field-deployable LA-ICP-AES is commercially viable. Eventual regulatory acceptance of field-deployable LA-ICP-AES, while not a simple process, is likely. Further refinement of certain processes and components of LA-ICP-AES will enhance the device`s sensitivity and accuracy.

  10. Multiple independent introductions of HIV-1 CRF01_AE identified in China: what are the implications for prevention?

    Directory of Open Access Journals (Sweden)

    Yassir F Abubakar

    Full Text Available BACKGROUND: HIV-1 CRF01_AE accounts for an important fraction of HIV infections in Asia including China, but little is known about the phylogenetic and evolutionary history of this CRF (circulating recombinant form. In the current study, we collected a large number of 1,957 CRF01_AE gag p17 sequences with known sampling year (1990-2010 from 5 global regions representing 15 countries to better understand the phylogenetic relationships and epidemic history of CRF01_AE strains in China. METHODOLOGY/PRINCIPAL FINDINGS: CRF01_AE gag p17 sequences were retrieved from public databases to explore phylogenetic relationships and phylogeographic dynamics of CRF01_AE in Asia by using maximum-likelihood phylogenetics and Bayesian coalescent-based analyses. We found close phylogenetic relationships between sequences from Thailand, Vietnam and China. Moreover, at least 5 independent introductions and 5 independent autochthonous clades of CRF01_AE, which descended from Thailand or Vietnam were identified in China from 1991 through 2003. CONCLUSION/SIGNIFICANCE: The current study not only defines the migration of CRF01_AE clades to/in Asia, but also demonstrates the criticalness of identifying the circulating strains in the population for the development of vaccine and microbicides.

  11. Improving Corrosion Resistance of Stainless Steel by Yttrium Addition: An AES Analysis

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The influence of Y addition on the distribution of element concentrations in the passive film of high silicon stainless steel formed in 93% H2SO4 was comparatively studied by using auger electron spectroscopy (AES). The results show that 0.2%Y addition increases the SiO2 proportion in the passive film of stainless steel so that the formation of SiO2 enriched passive film from silicon in the alloy is brought into full play.

  12. ECONOMIC MODEL FOR EVALUATION OF INTEGRAL COMPETITIVENESS OF AUTOMOTIVE ENTERPRISES (AE

    Directory of Open Access Journals (Sweden)

    A. F. Zubritsky

    2010-01-01

    Full Text Available The paper considers problems pertaining to evaluation of competitiveness of automotive enterprises in the field of international consignments. An economic model for determination of the integral AE competitiveness is proposed in the paper and the model permits to substitute an expert estimation in respect of some factors by their qualitative calculation on the basis of data on enterprise activity in the international consignment market.

  13. A Novel Image Cryptosystem Based on S-AES and Chaotic Map

    Directory of Open Access Journals (Sweden)

    Bai Lan

    2015-01-01

    Full Text Available This paper proposes a novel scheme based on simplified advanced encryption standard (S-AES for image encryption. Modified Arnold Map applied as diffusion technique for an image, and the key and dynamic S-box of encryption is generated by PWLCM. The goal is to balance rapidity and security of encryption. Experimental implementation has been done. This light encryption scheme shows resistance against chosen-plaintext attack and is suitable for sensor networks and IoT.

  14. AE$\\mathrm{\\bar{g}}$IS Experiment Positron Accumulator: Optimization and Control

    CERN Document Server

    Moura, Joao Pedro

    2013-01-01

    The present document describes my 8-week work project at the AE$\\mathrm{\\bar{g}}$IS experiment. The project can be divided into three main tasks: 1. Theoretical preparation; 2. Support at the experiment; and 3. Control of the ES075-2 Power Supply. A description of these tasks is presented. Special emphasis is put on the third task and further developments are proposed.

  15. Complementary Metal-Oxide-Silicon (CMOS)-Memristor Hybrid Nanoelectronics for Advanced Encryption Standard (AES) Encryption

    Science.gov (United States)

    2016-04-01

    structures . Devices were then characterized electrically to determine switching performance and behavior. Our results show that the metal TE plays a... details can be found in Table 1. The full chip design incorporates all of the resistive memory development structures in redundant rows along with CMOL...COMPLEMENTARY METAL -OXIDE-SILICON (CMOS)-MEMRISTOR HYBRID NANOELECTRONICS FOR ADVANCED ENCRYPTION STANDARD (AES) ENCRYPTION SUNY POLYTECHNIC

  16. Desktop system for accounting, audit, and research in A&E.

    Science.gov (United States)

    Taylor, C J; Brain, S G; Bull, F; Crosby, A C; Ferguson, D G

    1997-03-01

    The development of a database for audit, research, and accounting in accident and emergency (A&E) is described. The system uses a desktop computer, an optical scanner, sophisticated optical mark reader software, and workload management data. The system is highly flexible, easy to use, and at a cost of around 16,000 pounds affordable for larger departments wishing to move towards accounting. For smaller departments, it may be an alternative to full computerisation.

  17. [Determination of Ag, Cu, Zn and Cd in silver brazing filler metals by ICP-AES].

    Science.gov (United States)

    Yang, X

    1997-06-01

    A method of simultaneous and direct determination for Ag, Cu, Zn and Cd in silver brazing filler metals by ICP-AES is reported. The spectral interferences and effect of acidity have been investigated. Working conditions were optimized. The method has been applied to the analysis of silver brazing filler metals with RSD of 4-7% and recovery of 94-105%. This method was accurate, simple and rapid.

  18. Covering tree with stars

    DEFF Research Database (Denmark)

    Baumbach, Jan; Guo, Jian-Ying; Ibragimov, Rashid

    2013-01-01

    We study the tree edit distance problem with edge deletions and edge insertions as edit operations. We reformulate a special case of this problem as Covering Tree with Stars (CTS): given a tree T and a set of stars, can we connect the stars in by adding edges between them such that the resulting ...

  19. Covering tree with stars

    DEFF Research Database (Denmark)

    Baumbach, Jan; Guo, Jiong; Ibragimov, Rashid

    2015-01-01

    We study the tree edit distance problem with edge deletions and edge insertions as edit operations. We reformulate a special case of this problem as Covering Tree with Stars (CTS): given a tree T and a set of stars, can we connect the stars in by adding edges between them such that the resulting ...

  20. Magnetism in massive stars

    NARCIS (Netherlands)

    Henrichs, H.F.

    2012-01-01

    Stars with mass more than 8 solar masses end their lives as neutron stars, which we mostly observe as highly magnetized objects. Where does this magnetic field come from? Such a field could be formed during the collapse, or is a (modified) remnant of a fossil field since the birth of the star, or ot

  1. Managing the star performer.

    Science.gov (United States)

    Hills, Laura

    2013-01-01

    Our culture seems to be endlessly fascinated with its stars in entertainment, athletics, politics, and business, and holds fast to the idea that extraordinary talent accounts for an individual's extraordinary performance. At first glance, managing a star performer in your medical practice may seem like it would be an easy task. However, there's much more to managing a star performer than many practice managers realize. The concern is how to keep the star performer happy and functioning at a high level without detriment to the rest of the medical practice team. This article offers tips for practice managers who manage star performers. It explores ways to keep the star performer motivated, while at the same time helping the star performer to meld into the existing medical practice team. This article suggests strategies for redefining the star performer's role, for holding the star performer accountable for his or her behavior, and for coaching the star performer. Finally, this article offers practical tips for keeping the star performer during trying times, for identifying and cultivating new star performers, and for managing medical practice prima donnas.

  2. America's Star Libraries

    Science.gov (United States)

    Lyons, Ray; Lance, Keith Curry

    2009-01-01

    "Library Journal"'s new national rating of public libraries, the "LJ" Index of Public Library Service, identifies 256 "star" libraries. It rates 7,115 public libraries. The top libraries in each group get five, four, or three Michelin guide-like stars. All included libraries, stars or not, can use their scores to learn from their peers and improve…

  3. To rescue a star

    OpenAIRE

    1996-01-01

    Massless neutrinos are exchanged in a neutron star, leading to long range interactions. Many body forces of this type follow and we resum them. Their net contribution to the total energy is negligible as compared to the star mass. The stability of the star is not in danger, contrary to recent assertions.

  4. AE analysis of delamination crack propagation in carbon fiber-reinforced polymer materials

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Sang Jae; Arakawa, Kazuo [Kyushu University, kasuga (Japan); Chen, Dingding [National University of Defense Technology, Changsha (China); Han, Seung Wook; Choi, Nak Sam [Hanyang University, Seoul (Korea, Republic of)

    2015-01-15

    Delamination fracture behavior was investigated using acoustic emission (AE) analysis on carbon fiber-reinforced polymer (CFRP) samples manufactured using vacuum-assisted resin transfer molding (VARTM). CFRP plate was fabricated using unidirectional carbon fiber fabric with a lay-up of six plies [+30/-30]6 , and a Teflon film was inserted as a starter crack. Test pieces were sectioned from the inlet and vent of the mold, and packed between two rectangular epoxy plates to load using a universal testing machine. The AE signals were monitored during tensile loading using two sensors. The average tensile load of the inlet specimens was slightly larger than that of the vent specimens; however, the data exhibited significant scattering due to non-uniform resin distribution, and there was no statistically significant different between the strength of the samples sectioned from the inlet or outlet of the mold. Each of the specimens exhibited similar AE characteristics, regardless of whether they were from the inlet or vent of the mold. Four kinds of damage mechanism were observed: micro-cracking, fiber-resin matrix debonding, fiber pull-out, and fiber failure; and three stages of the crack propagation process were identified.

  5. Variations of thermospheric composition according to AE-C data and CTIP modelling

    Directory of Open Access Journals (Sweden)

    H. Rishbeth

    2004-01-01

    Full Text Available Data from the Atmospheric Explorer C satellite, taken at middle and low latitudes in 1975-1978, are used to study latitudinal and month-by-month variations of thermospheric composition. The parameter used is the "compositional Ρ-parameter", related to the neutral atomic oxygen/molecular nitrogen concentration ratio. The midlatitude data show strong winter maxima of the atomic/molecular ratio, which account for the "seasonal anomaly" of the ionospheric F2-layer. When the AE-C data are compared with the empirical MSIS model and the computational CTIP ionosphere-thermosphere model, broadly similar features are found, but the AE-C data give a more molecular thermosphere than do the models, especially CTIP. In particular, CTIP badly overestimates the winter/summer change of composition, more so in the south than in the north. The semiannual variations at the equator and in southern latitudes, shown by CTIP and MSIS, appear more weakly in the AE-C data. Magnetic activity produces a more molecular thermosphere at high latitudes, and at mid-latitudes in summer.

    Key words. Atmospheric composition and structure (thermosphere – composition and chemistry

  6. Low-power and area-optimized VLSI implementation of AES coprocessor for Zigbee system

    Institute of Scientific and Technical Information of China (English)

    LI Zhen-rong; ZHUANG Yi-qi; ZHANG Chao; JIN Gang

    2009-01-01

    A low-power and low-cost advanced encryption standard (AES) coprocessor is proposed for Zigbee system-on-a-chip (SoC) design. The cost and power consumption of the proposed AES coprocessor are reduced considerably by optimizing the architectures of SubBytes/InvSubBytes and MixColumns/InvMixColumns, integrating the encryption and deeryption procedures together by the method of resource sharing, and using the hierarchical power management strategy based on finite state machine (FSM) and clock gating (CG) technologies. Based on SMIC 0.18 μm complementary metal oxide semiconductor (CMOS) technology, the scale of the AES coprocessor is only about 10.5 kgate, the corresponding power consumption is 69.1 μW/MHz,and the throughput is 32 Mb/s, which is reasonable and sufficient for Zigbee system. Compared with other designs, the proposed architecture consumes less power and fewer hardware resources, which is conducive to the Zigbee system and other portable devices.

  7. LINFLUX-AE: A Turbomachinery Aeroelastic Code Based on a 3-D Linearized Euler Solver

    Science.gov (United States)

    Reddy, T. S. R.; Bakhle, M. A.; Trudell, J. J.; Mehmed, O.; Stefko, G. L.

    2004-01-01

    This report describes the development and validation of LINFLUX-AE, a turbomachinery aeroelastic code based on the linearized unsteady 3-D Euler solver, LINFLUX. A helical fan with flat plate geometry is selected as the test case for numerical validation. The steady solution required by LINFLUX is obtained from the nonlinear Euler/Navier Stokes solver TURBO-AE. The report briefly describes the salient features of LINFLUX and the details of the aeroelastic extension. The aeroelastic formulation is based on a modal approach. An eigenvalue formulation is used for flutter analysis. The unsteady aerodynamic forces required for flutter are obtained by running LINFLUX for each mode, interblade phase angle and frequency of interest. The unsteady aerodynamic forces for forced response analysis are obtained from LINFLUX for the prescribed excitation, interblade phase angle, and frequency. The forced response amplitude is calculated from the modal summation of the generalized displacements. The unsteady pressures, work done per cycle, eigenvalues and forced response amplitudes obtained from LINFLUX are compared with those obtained from LINSUB, TURBO-AE, ASTROP2, and ANSYS.

  8. Trigermanides AEGe{sub 3} (AE = Ca, Sr, Ba). Chemical bonding and superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Castillo, Rodrigo; Schnelle, Walter; Baranov, Alexey I.; Burkhardt, Ulrich; Bobnar, Matej; Cardoso-Gil, Raul; Schwarz, Ulrich; Grin, Yuri [Max-Planck-Institut fuer Chemische Physik Fester Stoffe, Dresden (Germany)

    2016-08-01

    The crystal structures of the trigermanides AEGe{sub 3}(tI32) (AE = Ca, Sr, Ba; space group I4/mmm, for SrGe{sub 3}: a = 7.7873(1), c = 12.0622(3) Aa) comprise Ge{sub 2} dumbbells forming layered Ge substructures which enclose embedded AE atoms. The chemical bonding analysis by application of the electron localizability approach reveals a substantial charge transfer from the AE atoms to the germanium substructure. The bonding within the dumbbells is of the covalent two-center type. A detailed analysis of SrGe{sub 3} reveals that the interaction on the bond-opposite side of the Ge{sub 2} groups is not lone pair-like - as it would be expected from the Zintl-like interpretation of the crystal structure with anionic Ge layers separated by alkaline-earth cations - but multi-center strongly polar between the Ge{sub 2} dumbbells and the adjacent metal atoms. Similar atomic interactions are present in CaGe{sub 3} and BaGe{sub 3}. The variation of the alkaline-earth metal has a merely insignificant influence on the superconducting transition temperatures in the s,p-electron compounds AEGe{sub 3}.

  9. Fault Diagnosis of Automobile Crane Power Steering System Aided by ICP-AES

    Directory of Open Access Journals (Sweden)

    Lidan Chen

    2013-01-01

    Full Text Available The objective of this paper is to evaluate an innovative application of inductively coupled plasma atomic emission spectroscopy (ICP-AES on the fault diagnosis of automobile crane hydraulic power steering (HPS system. Contents of Fe, Cu and Al were examined by ICP-AES in the oil samples of HPS system for four different mileages of Puyuan QY50H. The mileages were 2000-9000 km, 11000-19000 km, 21000-28000 km and 32000-40000 km separately. Database of major mental contents in automobile crane HPS system of Puyuan QY50H with different mileage were calibrated. Results showed that, major mental contents were increased with the increasing of driving mileage and the normal contents laid between two trend lines. Through the determination of mental contents in HPS oil sample and further compared them with the values in their database, we could not only evaluate the wear condition of automobile crane HPS system, but also helped to diagnose the faults without dissembled the problematic vehicle. The results further indicated that, in time maintenance, high quality and low cost reparation could be realized by the application of ICP-AES technology on fault diagnosis of automobile crane power steering system.

  10. Epistatic roles of E2 glycoprotein mutations in adaption of chikungunya virus to Aedes albopictus and Ae. aegypti mosquitoes.

    Directory of Open Access Journals (Sweden)

    Konstantin A Tsetsarkin

    Full Text Available Between 2005 and 2007 Chikungunya virus (CHIKV caused its largest outbreak/epidemic in documented history. An unusual feature of this epidemic is the involvement of Ae. albopictus as a principal vector. Previously we have demonstrated that a single mutation E1-A226V significantly changed the ability of the virus to infect and be transmitted by this vector when expressed in the background of well characterized CHIKV strains LR2006 OPY1 and 37997. However, in the current study we demonstrate that introduction of the E1-A226V mutation into the background of an infectious clone derived from the Ag41855 strain (isolated in Uganda in 1982 does not significantly increase infectivity for Ae. albopictus. In order to elucidate the genetic determinants that affect CHIKV sensitivity to the E1-A226V mutation in Ae. albopictus, the genomes of the LR2006 OPY1 and Ag41855 strains were used for construction of chimeric viruses and viruses with a specific combination of point mutations at selected positions. Based upon the midgut infection rates of the derived viruses in Ae. albopictus and Ae. aegypti mosquitoes, a critical role of the mutations at positions E2-60 and E2-211 on vector infection was revealed. The E2-G60D mutation was an important determinant of CHIKV infectivity for both Ae. albopictus and Ae. aegypti, but only moderately modulated the effect of the E1-A226V mutation in Ae. albopictus. However, the effect of the E2-I211T mutation with respect to mosquito infections was much more specific, strongly modifying the effect of the E1-A226V mutation in Ae. albopictus. In contrast, CHIKV infectivity for Ae. aegypti was not influenced by the E2-1211T mutation. The occurrence of the E2-60G and E2-211I residues among CHIKV isolates was analyzed, revealing a high prevalence of E2-211I among strains belonging to the Eastern/Central/South African (ECSA clade. This suggests that the E2-211I might be important for adaptation of CHIKV to some particular conditions

  11. AE-941, a multifunctional antiangiogenic compound: trials in renal cell carcinoma.

    Science.gov (United States)

    Bukowski, Ronald M

    2003-08-01

    The therapy of renal cell carcinoma remains a challenge for medical oncologists and urologists. During the past 10 years, the molecular abnormalities occurring in various subtypes of renal cancer, such as clear cell renal carcinoma, have been well described. The genetic abnormalities found in clear cell tumours involve chromosome 3p and, additionally, hypermethylation of the von Hippel-Lindau (VHL) gene can be detected. The VHL protein is involved in the angiogenic cascade in non-hypoxic conditions, and the possible role of mutant or hypermethylated VHL protein in promoting angiogenesis is, therefore, of interest. The majority of patients with renal cell carcinoma who receive treatment, such as IL-2 and/or IFN, fail and develop progressive disease. Therapy is therefore inadequate and novel approaches, such as those inhibiting angiogenesis, are of interest. The agent AE-941 (Neovostat trade mark; AEterna) was developed based on the observation that shark cartilage may contain biologically active inhibitors of angiogenesis. A variety of in vitro and in vivo activities of this preparation have been identified. At the molecular level, AE-941 appears to exhibit four different potential mechanisms of action: modulation of matrix proteases; inhibition of vascular endothelial growth factor binding to its receptor; induction of endothelial cell apoptosis; and stimulation of angiostatin production. The antitumour effects of AE-941 are seen in multiple murine models and involve not only effects on primary tumour growth but also on development of metastases. AE-941 is administered orally and has an excellent toxicity profile. Of interest are the findings in patients with renal cell carcinoma. Preliminary trials in this setting have suggested that responses to AE-941 occur and that patients receiving higher doses of this agent may have improved survival. Based on these preliminary data, a large, multi-institutional, randomised, Phase III trial of this agent has now been

  12. Optical and scintillation properties of Ce:(Gd8AE2)(SiO4)6O2 (AE = Mg, Ca, Sr and Ba) crystals

    Science.gov (United States)

    Igashira, Takuya; Mori, Masaki; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

    2017-02-01

    1% Ce-doped and non-doped (Gd8AE2)(SiO4)6O2 (AE = Mg, Ca, Sr and Ba) (denoted as GMS, GCS, GSrS and GBS, respectively) single crystals were grown by the Floating Zone (FZ) method to evaluate their optical and scintillation properties. The Ce:GCS and Ce:GSrS samples exhibited scintillation and photoluminescence (PL) around 400 nm due to the 5d-4f transitions of Ce3+. On the other hand, Ce:GMS and Ce:GBS showed much weaker emissions in the wavelength range of 500-650 nm, in which the origin was associated with the host matrices. The PL decay curves were approximated by a double exponential decay function for all the Ce-doped samples. The decay times ranged around 10-30 and 40-90 ns, and faster components coincided with those of the non-doped samples. The scintillation decay curves of Ce-doped samples, on the other hand, were approximated by single exponential functions with slower decay constants than those of PL decay. These constants were very similar to those of non-doped samples. In the X-ray induced afterglow measurements, Ce:GCS exhibited the lowest afterglow level. The pulse height spectrum of these samples showed a full-energy peak under 241Am 5.5 MeV α-ray irradiation. Among these samples, Ce:GSrS exhibited the highest light yield which was around 600 ph/5.5 MeV-α.

  13. Nuclear physics of stars

    CERN Document Server

    Iliadis, Christian

    2015-01-01

    Most elements are synthesized, or ""cooked"", by thermonuclear reactions in stars. The newly formed elements are released into the interstellar medium during a star's lifetime, and are subsequently incorporated into a new generation of stars, into the planets that form around the stars, and into the life forms that originate on the planets. Moreover, the energy we depend on for life originates from nuclear reactions that occur at the center of the Sun. Synthesis of the elements and nuclear energy production in stars are the topics of nuclear astrophysics, which is the subject of this book

  14. Magnetic chemically peculiar stars

    CERN Document Server

    Schöller, Markus

    2015-01-01

    Chemically peculiar (CP) stars are main-sequence A and B stars with abnormally strong or weak lines for certain elements. They generally have magnetic fields and all observables tend to vary with the same period. Chemically peculiar stars provide a wealth of information; they are natural atomic and magnetic laboratories. After a brief historical overview, we discuss the general properties of the magnetic fields in CP stars, describe the oblique rotator model, explain the dependence of the magnetic field strength on the rotation, and concentrate at the end on HgMn stars.

  15. Validation of the new trapped environment AE9/AP9/SPM at low Earth orbit

    Science.gov (United States)

    Badavi, Francis F.

    2014-09-01

    The completion of the international space station (ISS) in 2011 has provided the space research community an ideal proving ground for future long duration human activities in space. Ionizing radiation measurements in ISS form the ideal tool for the validation of radiation environmental models, nuclear transport codes and nuclear reaction cross sections. Indeed, prior measurements on the space transportation system (STS; shuttle) provided vital information impacting both the environmental models and the nuclear transport code developments by indicating the need for an improved dynamic model of the low Earth orbit (LEO) trapped environment. Additional studies using thermo-luminescent detector (TLD), tissue equivalent proportional counter (TEPC) area monitors, and computer aided design (CAD) model of earlier ISS configurations, confirmed STS observations that, as input, computational dosimetry requires an environmental model with dynamic and directional (anisotropic) behavior, as well as an accurate six degree of freedom (DOF) definition of the vehicle attitude and orientation along the orbit of ISS. At LEO, a vehicle encounters exposure from trapped particles and attenuated galactic cosmic rays (GCR). Within the trapped field, a challenge arises from properly estimating the amount of exposure acquired. There exist a number of models to define the intensities of the trapped particles during the solar quiet and active times. At active times, solar energetic particles (SEP) generated by solar flare or coronal mass ejection (CME) also contribute to the exposure at high northern and southern latitudes. Among the more established trapped models are the historic and popular AE8/AP8, dating back to the 1980s, the historic and less popular CRRES electron/proton, dating back to 1990s and the recently released AE9/AP9/SPM. The AE9/AP9/SPM model is a major improvement over the older AE8/AP8 and CRRES models. This model is derived from numerous measurements acquired over four

  16. THE FIRST STARS

    Directory of Open Access Journals (Sweden)

    Daniel J. Whalen

    2013-12-01

    Full Text Available Pop III stars are the key to the character of primeval galaxies, the first heavy elements, the onset of cosmological reionization, and the seeds of supermassive black holes. Unfortunately, in spite of their increasing sophistication, numerical models of Pop III star formation cannot yet predict the masses of the first stars. Because they also lie at the edge of the observable universe, individual Pop III stars will remain beyond the reach of observatories for decades to come, and so their properties are unknown. However, it will soon be possible to constrain their masses by direct detection of their supernovae, and by reconciling their nucleosynthetic yields to the chemical abundances measured in ancient metal-poor stars in the Galactic halo, some of which may bear the ashes of the first stars. Here, I review the state of the art in numerical simulations of primordial stars and attempts to directly and indirectly constrain their properties.

  17. Research on FC-AE-1553B Network Performance with Different Topology Structure%不同拓扑结构FC-AE-1553B网络性能研究

    Institute of Scientific and Technical Information of China (English)

    陈勇; 林宝军; 张善从

    2011-01-01

    Three kinds of FC-AE-1553B network topology structures are studied in this paper, including point-to-point topology, fabric topology and arbitrated loop topology. The Markov model of FC-AE-1553B network is built, and the effect of the single-point fault on three kinds of FC-AE-1553B network is analyzed. Simulation results show that point-to-point topology has the lowest data transmission delays from NT node to NC node, and the fabric topology lowest data transmission delays from NT node to NT node.%研究点对点、交换式与仲裁环3种不同拓扑结构的网络,建立FC-AE- 1553B网络的Markov模型,并分析单点故障对不同拓扑结构总线的影响.仿真结果表明,基于点对点结构的FC-AE-1553B网络在传输NT 节点到NC节点的数据流时,具有最小时延,基于交换机实现的FC-AE-1553B网络在传输NT节点到NT节点的数据时,传输性能较优.

  18. The Epidemic Dynamics of Four Major Lineages of HIV-1 CRF01_AE Strains After Their Introduction into China.

    Science.gov (United States)

    Zeng, Haiyan; Li, Tingting; Wang, Yan; Sun, Binlian; Yang, Rongge

    2016-05-01

    The epidemic of HIV-1 CRF01_AE in China was driven by multiple lineages of HIV-1 viruses introduced in the 1990s and increasing; it is important to investigate their epidemic status in China. In this study, we download all available CRF01_AE sequences (n = 2,931) from China and their associated epidemiological information in the Los Alamos HIV database for our analysis to explore their epidemic status in China. The results showed there were 11 distinct clusters of CRF01_AE strains in China, and 4 major clusters that accounted for 80.0% (1,793/2,241) of Chinese CRF01_AE strains in total had led a real epidemic. Clusters 1 and 2 were epidemic among heterosexuals and injecting drug users in southern and southwestern China, while Clusters 3 and 4 were predominant among homosexuals in eastern and central China and northeastern China, respectively. HIV-1 CRF01_AE strains detected in heterosexuals had the most complex characteristic, underscoring its important role in the occurrence of multiple CRF01_AE lineages. Furthermore, epidemic history reconstruction analysis using the birth-death susceptible-infected-removed package revealed that the four clusters had gone through varying epidemic stages. Clusters 2 and 3 were near the peak of the local epidemic, while Clusters 1 and 4 were just in the very early stage of their epidemic. The epidemic status of CRF01_AE clusters in the future is mainly determined by the effect of prevention and control. Our study provides new insights into the understanding of the epidemic dynamics of CRF01_AE in China.

  19. Star Clusters within FIRE

    Science.gov (United States)

    Perez, Adrianna; Moreno, Jorge; Naiman, Jill; Ramirez-Ruiz, Enrico; Hopkins, Philip F.

    2017-01-01

    In this work, we analyze the environments surrounding star clusters of simulated merging galaxies. Our framework employs Feedback In Realistic Environments (FIRE) model (Hopkins et al., 2014). The FIRE project is a high resolution cosmological simulation that resolves star forming regions and incorporates stellar feedback in a physically realistic way. The project focuses on analyzing the properties of the star clusters formed in merging galaxies. The locations of these star clusters are identified with astrodendro.py, a publicly available dendrogram algorithm. Once star cluster properties are extracted, they will be used to create a sub-grid (smaller than the resolution scale of FIRE) of gas confinement in these clusters. Then, we can examine how the star clusters interact with these available gas reservoirs (either by accreting this mass or blowing it out via feedback), which will determine many properties of the cluster (star formation history, compact object accretion, etc). These simulations will further our understanding of star formation within stellar clusters during galaxy evolution. In the future, we aim to enhance sub-grid prescriptions for feedback specific to processes within star clusters; such as, interaction with stellar winds and gas accretion onto black holes and neutron stars.

  20. Multiplicity of massive stars

    CERN Document Server

    Preibisch, T; Zinnecker, H; Preibisch, Thomas; Weigelt, Gerd; Zinnecker, Hans

    2000-01-01

    We discuss the observed multiplicity of massive stars and implications on theories of massive star formation. After a short summary of the literature on massive star multiplicity, we focus on the O- and B-type stars in the Orion Nebula Cluster, which constitute a homogenous sample of very young massive stars. 13 of these stars have recently been the targets of a bispectrum speckle interferometry survey for companions. Considering the visual and also the known spectroscopic companions of these stars, the total number of companions is at least 14. Extrapolation with correction for the unresolved systems suggests that there are at least 1.5 and perhaps as much as 4 companions per primary star on average. This number is clearly higher than the mean number of about 0.5 companions per primary star found for the low-mass stars in the general field population and also in the Orion Nebula cluster. This suggests that a different mechanism is at work in the formation of high-mass multiple systems in the dense Orion Nebu...

  1. Dark stars: a review.

    Science.gov (United States)

    Freese, Katherine; Rindler-Daller, Tanja; Spolyar, Douglas; Valluri, Monica

    2016-06-01

    Dark stars are stellar objects made (almost entirely) of hydrogen and helium, but powered by the heat from dark matter annihilation, rather than by fusion. They are in hydrostatic and thermal equilibrium, but with an unusual power source. Weakly interacting massive particles (WIMPs), among the best candidates for dark matter, can be their own antimatter and can annihilate inside the star, thereby providing a heat source. Although dark matter constitutes only [Formula: see text]0.1% of the stellar mass, this amount is sufficient to power the star for millions to billions of years. Thus, the first phase of stellar evolution in the history of the Universe may have been dark stars. We review how dark stars come into existence, how they grow as long as dark matter fuel persists, and their stellar structure and evolution. The studies were done in two different ways, first assuming polytropic interiors and more recently using the MESA stellar evolution code; the basic results are the same. Dark stars are giant, puffy (∼10 AU) and cool (surface temperatures  ∼10 000 K) objects. We follow the evolution of dark stars from their inception at  ∼[Formula: see text] as they accrete mass from their surroundings to become supermassive stars, some even reaching masses  >[Formula: see text] and luminosities  >[Formula: see text], making them detectable with the upcoming James Webb Space Telescope. Once the dark matter runs out and the dark star dies, it may collapse to a black hole; thus dark stars may provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation may exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The current review briefly discusses dark stars existing today, but focuses on the early generation of dark stars.

  2. Dark stars: a review

    Science.gov (United States)

    Freese, Katherine; Rindler-Daller, Tanja; Spolyar, Douglas; Valluri, Monica

    2016-06-01

    Dark stars are stellar objects made (almost entirely) of hydrogen and helium, but powered by the heat from dark matter annihilation, rather than by fusion. They are in hydrostatic and thermal equilibrium, but with an unusual power source. Weakly interacting massive particles (WIMPs), among the best candidates for dark matter, can be their own antimatter and can annihilate inside the star, thereby providing a heat source. Although dark matter constitutes only ≲ 0.1% of the stellar mass, this amount is sufficient to power the star for millions to billions of years. Thus, the first phase of stellar evolution in the history of the Universe may have been dark stars. We review how dark stars come into existence, how they grow as long as dark matter fuel persists, and their stellar structure and evolution. The studies were done in two different ways, first assuming polytropic interiors and more recently using the MESA stellar evolution code; the basic results are the same. Dark stars are giant, puffy (˜10 AU) and cool (surface temperatures  ˜10 000 K) objects. We follow the evolution of dark stars from their inception at  ˜1{{M}⊙} as they accrete mass from their surroundings to become supermassive stars, some even reaching masses  >{{10}6}{{M}⊙} and luminosities  >{{10}10}{{L}⊙} , making them detectable with the upcoming James Webb Space Telescope. Once the dark matter runs out and the dark star dies, it may collapse to a black hole; thus dark stars may provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation may exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The current review briefly discusses dark stars existing today, but focuses on the early generation of dark stars.

  3. Star-Branched Polymers (Star Polymers)

    KAUST Repository

    Hirao, Akira

    2015-09-01

    The synthesis of well-defined regular and asymmetric mixed arm (hereinafter miktoarm) star-branched polymers by the living anionic polymerization is reviewed in this chapter. In particular, much attention is being devoted to the synthetic development of miktoarm star polymers since 2000. At the present time, the almost all types of multiarmed and multicomponent miktoarm star polymers have become feasible by using recently developed iterative strategy. For example, the following well-defined stars have been successfully synthesized: 3-arm ABC, 4-arm ABCD, 5-arm ABCDE, 6-arm ABCDEF, 7-arm ABCDEFG, 6-arm ABC, 9-arm ABC, 12-arm ABC, 13-arm ABCD, 9-arm AB, 17-arm AB, 33-arm AB, 7-arm ABC, 15-arm ABCD, and 31-arm ABCDE miktoarm star polymers, most of which are quite new and difficult to synthesize by the end of the 1990s. Several new specialty functional star polymers composed of vinyl polymer segments and rigid rodlike poly(acetylene) arms, helical polypeptide, or helical poly(hexyl isocyanate) arms are introduced.

  4. Touchstone Stars: Highlights from the Cool Stars 18 Splinter Session

    CERN Document Server

    Mann, Andrew W; Boyajian, Tabetha; Gaidos, Eric; von Braun, Kaspar; Feiden, Gregory A; Metcalfe, Travis; Swift, Jonathan J; Curtis, Jason L; Deacon, Niall R; Filippazzo, Joseph C; Gillen, Ed; Hejazi, Neda; Newton, Elisabeth R

    2014-01-01

    We present a summary of the splinter session on "touchstone stars" -- stars with directly measured parameters -- that was organized as part of the Cool Stars 18 conference. We discuss several methods to precisely determine cool star properties such as masses and radii from eclipsing binaries, and radii and effective temperatures from interferometry. We highlight recent results in identifying and measuring parameters for touchstone stars, and ongoing efforts to use touchstone stars to determine parameters for other stars. We conclude by comparing the results of touchstone stars with cool star models, noting some unusual patterns in the differences.

  5. Access Driven Cache Timing Attack Against AES%AES访问驱动Cache计时攻击

    Institute of Scientific and Technical Information of China (English)

    赵新杰; 王韬; 郭世泽; 郑媛媛

    2011-01-01

    Firstly, this paper displays an access driven Cache timing attack model, proposes non-elimination and elimination two general methods to analyze Cache information leakage during AES encryption, and builds the Cache information leakage model. Next, it uses quantitative analysis to attack a sample with the above elimination analysis method, and provides some solutions for the potential problems of a real attack. Finally, this paper describes 12 local and remote attacks on AES in OpenSSL v.0.9.Sa, v.0.9.Sj. Experiment results demonstrate that:the access driven Cache timing attack has strong applicability in both local and remote environments; the AES lookup table and Cache structure decide that AES is vulnerable to this type of attack, the least sample size required to recover a full AES key is about 13; the last round A.ES implementation in OpenSSL v.0.9.Sj, which abandoned the T4 lookup table, cannot secure itself from the access driven Cache timing attack; the attack results strongly verify the correctness of the quantitative Cache information leakage theory and key analysis methods above.%首先给出了访问驱动Cache计时攻击的模型,提出了该模型下直接分析、排除分析两种通用的AES加密泄漏Cache信息分析方法;然后建立了AES加密Cache信息泄露模型,并在此基础上对排除分析攻击所需样本量进行了定量分析,给出了攻击中可能遇到问题的解决方案;最后结合OpenSSL v.0.9.8a,v.0.9.8j中两种典型的AES实现在Windows环境下进行了本地和远程攻击共12个实验.实验结果表明,访问驱动Cache计时攻击在本地和远程均具有良好的可行性;AES查找表和Cache结构本身决定了AES易遭受访问驱动Cache计时攻击威胁,攻击最小样本量仅为13;去除T4表的OpenSSL v.0.9.8j中AES最后一轮实现并不能防御该攻击;实验结果多次验证了AES加密Cache信息泄露和密钥分析理论的正确性.

  6. The Growing-up of a Star

    Science.gov (United States)

    2008-01-01

    Using ESO's Very Large Telescope Interferometer, astronomers have probed the inner parts of the disc of material surrounding a young stellar object, witnessing how it gains its mass before becoming an adult. ESO PR Photo 03/08 ESO PR Photo 03a/08 The disc around MWC 147 (Artist's Impression) The astronomers had a close look at the object known as MWC 147, lying about 2,600 light years away towards the constellation of Monoceros ('the Unicorn'). MWC 147 belongs to the family of Herbig Ae/Be objects. These have a few times the mass of our Sun and are still forming, increasing in mass by swallowing material present in a surrounding disc. MWC 147 is less than half a million years old. If one associated the middle-aged, 4.6 billion year old Sun with a person in his early forties, MWC 147 would be a 1-day-old baby [1]. The morphology of the inner environment of these young stars is however a matter of debate and knowledge of it is important to better understand how stars and their cortège of planets form. The astronomers Stefan Kraus, Thomas Preibisch, and Keiichi Ohnaka have used the four 8.2-m Unit Telescopes of ESO's Very Large Telescope to this purpose, combining the light from two or three telescopes with the MIDI and AMBER instruments. "With our VLTI/MIDI and VLTI/AMBER observations of MWC147, we combine, for the first time, near- and mid-infrared interferometric observations of a Herbig Ae/Be star, providing a measurement of the disc size over a wide wavelength range [2]," said Stefan Kraus, lead-author of the paper reporting the results. "Different wavelength regimes trace different temperatures, allowing us to probe the disc's geometry on the smaller scale, but also to constrain how the temperature changes with the distance from the star." The near-infrared observations probe hot material with temperatures of up to a few thousand degrees in the innermost disc regions, while the mid-infrared observations trace cooler dust further out in the disc. The

  7. STAR in CTO PCI: When is STAR not a star?

    Science.gov (United States)

    Hira, Ravi S; Dean, Larry S

    2016-04-01

    Subintimal tracking and reentry (STAR) has been used as a bailout strategy and involves an uncontrolled dissection and recanalization into the distal lumen to reestablish vessel patency. In the current study, thrombolysis in myocardial infarction (TIMI) flow < 3 was the only variable which they found to be significantly associated with restenosis and reocclusion after stent placement. It may be reasonable to consider second generation drug eluting stent placement in patients receiving STAR that have TIMI 3 flow, however, this should only be done if there is no compromise of major side branches. If unsure, we recommend to perform balloon angioplasty without stenting.

  8. Pestalofones A-E, bioactive cyclohexanone derivatives from the plant endophytic fungus Pestalotiopsis fici.

    Science.gov (United States)

    Liu, Ling; Liu, Shuchun; Chen, Xulin; Guo, Liangdong; Che, Yongsheng

    2009-01-15

    Pestalofones A-E (1-5), five new cyclohexanone derivatives, have been isolated from cultures of the plant endophytic fungus Pestalotiopsis fici, along with the known compounds, isosulochrin (6), isosulochrin dehydrate (7), and iso-A82775C (8). The structures of 1-5 were determined by NMR spectroscopy, and the absolute configuration of 1 was assigned using the modified Mosher method. Compounds 1, 2, and 5 displayed inhibitory effects on HIV-1 replication in C8166 cells, whereas 3 and 5 showed significant antifungal activity against Aspergillus fumigatus.

  9. Multipactor suppressing titanium nitride thin films analyzed through XPS and AES

    Energy Technology Data Exchange (ETDEWEB)

    Castro C, M.; Durrer, W.; Lopez, J. A.; Pinales, L. A. [Physics Department, University of Texas, El Paso TX 79968 (United States); Encinas B, C.; Moller, D. [Centro de Investigacion en Materiales Avanzados S. C., Miguel de Cervantes Saavedra 120, Complejo Industrial Chihuahua, 31109 Chihuahua (Mexico)

    2008-02-15

    Cathodic-magnetron-deposited titanium nitride films were grown on anodized aluminum substrates and studied via AES and XPS spectroscopies to determine their depth-dependence composition. As it is well known, the native oxide grown on aluminum does not make the substrate impervious to radio frequency damage, and typically a thin film coating is needed to suppress substrate damage. In this article we present the profile composition of titanium nitride films, used as a protective coating for aluminum, that underwent prior conditioning through anodization, observed after successive sputtering stages. (Author)

  10. Synthesis of hybrid sol-gel coatings for corrosion protection of we54-ae magnesium alloy

    Science.gov (United States)

    Hernández-Barrios, C. A.; Duarte, N. Z.; Hernández, L. M.; Peña, D. Y.; Coy, A. E.; Viejo, F.

    2013-11-01

    The present work shows some preliminary results related to the synthesis, characterization and corrosion evaluation of different hybrid sol-gel coatings applied on the WE54-AE magnesium alloy attending to the two experimental variables, i.e. the precursors ratio and the aging time, which may affect the quality and the electrochemical properties of the coatings resultant. The experimental results confirmed that, under some specific experimental conditions, it was possible to obtain homogeneous and uniform, porous coatings with good corrosion resistance that also permit to accommodate corrosion inhibitors.

  11. Allimacrosides A-E, new steroidal glycosides from Allium macrostemon Bunge.

    Science.gov (United States)

    Kim, Yun Sik; Suh, Won Se; Park, Kyoung Jin; Choi, Sang Un; Lee, Kang Ro

    2017-02-01

    A new pregnane-type steroidal glycoside (1), two new spirostane-type steroidal glycosides (2, 3), and two new furostane-type steroidal glycosides (4, 5), named allimacrosides A-E, together with four known compounds (6-9) were isolated from a 80% MeOH extract of Allium macrostemon Bunge. The identification and structural elucidation of these compounds were based on their 1D- and 2D-NMR spectra, and HR-FAB-MS data analysis. The isolated compounds were tested for cytotoxicity against four human tumor cell lines in vitro using the sulforhodamine B bioassay.

  12. Determination of soil micronutrients (Fe, Cu, Mn, B) extracted by Mehlich 3 using MP-AES

    Science.gov (United States)

    Krebstein, Kadri; Tõnutare, Tõnu; Rodima, Ako; Kõlli, Raimo; Künnapas, Allan; Rebane, Jaanus; Penu, Priit; Vennik, Kersti; Soobik, Liina

    2015-04-01

    The total concentration of micronutrients in soils is not a good predictor of its bioavailability and solubility. Therefore, during the decades several methods for the determination of plant availability and extractable fraction of micro- and macronutrients in soil were developed. Among several methods Mehlich 3 is the most appropriate due to its suitability for extracting soil micro- and macronutrients simultaneously. The AAS (atomic absorption spectroscopic) and ICP (inductively coupled plasma) methods are widely used for the analysis of microelements today. In 2011 the third method was added to this list with the appearance of the microwave plasma atomic emission spectrometer (MP-AES). This multielemental analytical equipment has a high potential in the soil analysis. Up to now there have been made some experiments for the use of MP-AES in soil and geological material analysis. But there is no information about the analysis of soil micronutrients extracted according to Mehlich 3 method and determined with the MP-AES. Due to the differences in atomization conditions the different emission and absorption lines are used in different instrumental methods. Therefore it is very important to choose the most suitable emission lines and the best atomization conditions. From the analytical viewpoint it is important to get coincidental results with other instrumental methods and from the agronomical point of view it is important to know the difference between AAS and ICP methods. For the experiment 51 soil samples were used. The samples were collected from A horizons of agricultural lands. The pH range was from 4.7 to 7.5 and organic matter content from 1.4 to 7.8%. The content of Mehlich 3 extractable micronutrients was determined using ICP and MP instrumental methods. The micronutrient contents ranged as follows: Fe - from 170 to 470 mg kg-1, Mn - from 5 to 190 mg kg-1, Cu - from 0.3 to 4.5 mg kg-1, B - from 0.2 to 2.1 mg kg-1. The optimal instrumental settings for iron

  13. Aerosol absorption coefficient and Equivalent Black Carbon by parallel operation of AE31 and AE33 aethalometers at the Zeppelin station, Ny Ålesund, Svalbard

    Science.gov (United States)

    Eleftheriadis, Konstantinos; Kalogridis, Athina-Cerise; Vratolis, Sterios; Fiebig, Markus

    2016-04-01

    Light absorbing carbon in atmospheric aerosol plays a critical role in radiative forcing and climate change. Despite the long term measurements across the Arctic, comparing data obtained by a variety of methods across stations requires caution. A method for extracting the aerosol absorption coefficient from data obtained over the decades by filter based instrument is still under development. An IASOA Aerosol working group has been initiated to address this and other cross-site aerosol comparison opportunities. Continuous ambient measurements of EBC/light attenuation by means of a Magee Sci. AE-31 aethalometer operating at the Zeppelinfjellet station (474 m asl; 78°54'N, 11°53'E), Ny Ålesund, Svalbard, have been available since 2001 (Eleftheriadis et al, 2009), while a new aethalometer model (AE33, Drinovec et al, 2014) has been installed to operate in parallel from the same inlet since June 2015. Measurements are recorded by a Labview routine collecting all available parameters reported by the two instrument via RS232 protocol. Data are reported at 1 and 10 minute intervals as averages for EBC (μg m-3) and aerosol absorption coefficients (Mm-1) by means of routine designed to report Near Real Time NRT data at the EBAS WDCA database (ebas.nilu.no) Results for the first 6 month period are reported here in an attempt to evaluate comparative performance of the two instruments in terms of their response with respect to the variable aerosol load of light absorbing carbon during the warm and cold seasons found in the high arctic. The application of available conversion schemes for obtaining the absorption coefficient by the two instruments is found to demonstrate a marked difference in their output. During clean periods of low aerosol load (EBC agreement with regression slope for the 880 nm signal between the two at ~ 0.9 compared to a slope at ~ 0.6 during the period of higher absorbing carbon loads (400Arctic: Measurements at Zeppelin station, Ny-Ålesund, Svalbard

  14. The First Stars

    Science.gov (United States)

    Yoshida, Naoki

    2010-10-01

    The standard cosmological model predicts that the first cosmological objects are formed when the age of the universe is a few hundred million years. Recent theoretical studies and numerical simulations consistently suggest that the first objects are very massive primordial stars. We introduce the key physics and explain why the first stars are thought to be massive, rather than to be low-mass stars. The state-of-the-art simulations include all the relevant atomic and molecular physics to follow the thermal evolution of a prestellar gas cloud to very high ``stellar'' densities. Evolutionary calculations of the primordial stars suggest the formation of massive blackholes in the early universe. Finally, we show the results from high-resolution simulations of star formation in a low-metallicity gas. Vigorous fragmentation is triggered in a star-forming gas cloud at a metallicity of as low as Z = 10-5Zsolar.

  15. Ae4 (Slc4a9) Anion Exchanger Drives Cl- Uptake-dependent Fluid Secretion by Mouse Submandibular Gland Acinar Cells.

    Science.gov (United States)

    Peña-Münzenmayer, Gaspar; Catalán, Marcelo A; Kondo, Yusuke; Jaramillo, Yasna; Liu, Frances; Shull, Gary E; Melvin, James E

    2015-04-24

    Transcellular Cl(-) movement across acinar cells is the rate-limiting step for salivary gland fluid secretion. Basolateral Nkcc1 Na(+)-K(+)-2Cl(-) cotransporters play a critical role in fluid secretion by promoting the intracellular accumulation of Cl(-) above its equilibrium potential. However, salivation is only partially abolished in the absence of Nkcc1 cotransporter activity, suggesting that another Cl(-) uptake pathway concentrates Cl(-) ions in acinar cells. To identify alternative molecular mechanisms, we studied mice lacking Ae2 and Ae4 Cl(-)/HCO3 (-) exchangers. We found that salivation stimulated by muscarinic and β-adrenergic receptor agonists was normal in the submandibular glands of Ae2(-/-) mice. In contrast, saliva secretion was reduced by 35% in Ae4(-/-) mice. The decrease in salivation was not related to loss of Na(+)-K(+)-2Cl(-) cotransporter or Na(+)/H(+) exchanger activity in Ae4(-/-) mice but correlated with reduced Cl(-) uptake during β-adrenergic receptor activation of cAMP signaling. Direct measurements of Cl(-)/HCO3 (-) exchanger activity revealed that HCO3 (-)-dependent Cl(-) uptake was reduced in the acinar cells of Ae2(-/-) and Ae4(-/-) mice. Moreover, Cl(-)/HCO3 (-) exchanger activity was nearly abolished in double Ae4/Ae2 knock-out mice, suggesting that most of the Cl(-)/HCO3 (-) exchanger activity in submandibular acinar cells depends on Ae2 and Ae4 expression. In conclusion, both Ae2 and Ae4 anion exchangers are functionally expressed in submandibular acinar cells; however, only Ae4 expression appears to be important for cAMP-dependent regulation of fluid secretion.

  16. Fingerprints of giant planets in the photospheres of Herbig stars

    CERN Document Server

    Kama, Mihkel; Pinilla, Paola

    2015-01-01

    Around 2% of all A stars have photospheres depleted in refractory elements. This is hypothesized to arise from a preferential accretion of gas rather than dust, but the specific processes and the origin of the material -- circum- or interstellar -- are not known. The same depletion is seen in 30% of young, disk-hosting Herbig Ae/Be stars. We investigate whether the chemical peculiarity originates in a circumstellar disk. Using a sample of systems for which both the stellar abundances and the protoplanetary disk structure are known, we find that stars hosting warm, flaring group I disks typically have Fe, Mg and Si depletions of 0.5 dex compared to the solar-like abundances of stars hosting cold, flat group II disks. The volatile, C and O, abundances in both sets are identical. Group I disks are generally transitional, having radial cavities depleted in millimetre-sized dust grains, while those of group II are usually not. Thus we propose that the depletion of heavy elements emerges as Jupiter-like planets blo...

  17. Imaging the water-snow line during a protostellar outburst

    CERN Document Server

    Cieza, Lucas A; Tobin, John; Bos, Steven P; Williams, Jonathan P; Perez, Sebastian; Zhu, Zhaohuan; Caceres, Claudio; Canovas, Hector; Dunham, Michael M; Hales, Antonio; Prieto, Jose L; Principe, David A; Schreiber, Matthias R; Ruiz-Rodriguez, Dary; Zurlo, Alice

    2016-01-01

    A snow-line is the region of a protoplanetary disk at which a major volatile, such as water or carbon monoxide, reaches its condensation temperature. Snow-lines play a crucial role in disk evolution by promoting the rapid growth of ice-covered grains. Signatures of the carbon monoxide snow-line (at temperatures of around 20 kelvin) have recently been imaged in the disks surrounding the pre-main-sequence stars TW Hydra and HD163296, at distances of about 30 astronomical units (au) from the star. But the water snow-line of a protoplanetary disk (at temperatures of more than 100 kelvin) has not hitherto been seen, as it generally lies very close to the star (less than 5 au away for solar-type stars). Water-ice is important because it regulates the efficiency of dust and planetesimal coagulation, and the formation of comets, ice giants and the cores of gas giants. Here we report images at 0.03-arcsec resolution (12 au) of the protoplanetary disk around V883 Ori, a protostar of 1.3 solar masses that is undergoing ...

  18. Strange nonchaotic stars

    CERN Document Server

    Lindner, John F; Kia, Behnam; Hippke, Michael; Learned, John G; Ditto, William L

    2015-01-01

    The unprecedented light curves of the Kepler space telescope document how the brightness of some stars pulsates at primary and secondary frequencies whose ratios are near the golden mean, the most irrational number. A nonlinear dynamical system driven by an irrational ratio of frequencies generically exhibits a strange but nonchaotic attractor. For Kepler's "golden" stars, we present evidence of the first observation of strange nonchaotic dynamics in nature outside the laboratory. This discovery could aid the classification and detailed modeling of variable stars.

  19. Interacting binary stars

    CERN Document Server

    Sahade, Jorge; Ter Haar, D

    1978-01-01

    Interacting Binary Stars deals with the development, ideas, and problems in the study of interacting binary stars. The book consolidates the information that is scattered over many publications and papers and gives an account of important discoveries with relevant historical background. Chapters are devoted to the presentation and discussion of the different facets of the field, such as historical account of the development in the field of study of binary stars; the Roche equipotential surfaces; methods and techniques in space astronomy; and enumeration of binary star systems that are studied

  20. Strange Nonchaotic Stars

    Science.gov (United States)

    Lindner, John F.; Kohar, Vivek; Kia, Behnam; Hippke, Michael; Learned, John G.; Ditto, William L.

    2015-08-01

    Exploiting the unprecedented capabilities of the planet-hunting Kepler space telescope, which stared at 150 000 stars for four years, we discuss recent evidence that certain stars dim and brighten in complex patterns with fractal features. Such stars pulsate at primary and secondary frequencies whose ratios are near the famous golden mean, the most irrational number. A nonlinear system driven by an irrational ratio of frequencies is generically attracted toward a “strange” behavior that is geometrically fractal without displaying the “butterfly effect” of chaos. Strange nonchaotic attractors have been observed in laboratory experiments and have been hypothesized to describe the electrochemical activity of the brain, but a bluish white star 16 000 light years from Earth in the constellation Lyra may manifest, in the scale-free distribution of its minor frequency components, the first strange nonchaotic attractor observed in the wild. The recognition of stellar strange nonchaotic dynamics may improve the classification of these stars and refine the physical modeling of their interiors. We also discuss nonlinear analysis of other RR Lyrae stars in Kepler field of view and discuss some toy models for modeling these stars.References: 1) Hippke, Michael, et al. "Pulsation period variations in the RRc Lyrae star KIC 5520878." The Astrophysical Journal 798.1 (2015): 42.2) Lindner, John F., et al. "Strange nonchaotic stars." Phys. Rev. Lett. 114, 054101 (2015)

  1. ENERGY STAR Unit Reports

    Data.gov (United States)

    Department of Housing and Urban Development — These quarterly Federal Fiscal Year performance reports track the ENERGY STAR qualified HOME units that Participating Jurisdictions record in HUD's Integrated...

  2. NuSTAR results and future plans for magnetar and rotation-powered pulsar observations

    CERN Document Server

    An, Hongjun; Archibald, Robert; Bachetti, Matteo; Bhalerao, Varun; Bellm, Eric C; Beloborodov, Andrei M; Boggs, Steven E; Chakrabarty, Deepto; Christensen, Finn E; Craig, William W; Dufour, Francois; Forster, Karl; Gotthelf, Eric V; Grefenstette, Brian W; Hailey, Charles J; Harrison, Fiona A; Hascoet, Romain; Kitaguchi, Takao; Kouveliotou, Chryssa; Madsen, Kristin K; Mori, Kaya; Pivovaroff, Michael J; Rana, Vikram R; Stern, Daniel; Tendulkar, Shriharsh; Tomsick, John A; Vogel, Julia K; Zhang, William W

    2014-01-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR) is the first focusing hard X-ray mission in orbit and operates in the 3-79 keV range. NuSTAR's sensitivity is roughly two orders of magnitude better than previous missions in this energy band thanks to its superb angular resolution. Since its launch in 2012 June, NuSTAR has performed excellently and observed many interesting sources including four magnetars, two rotation-powered pulsars and the cataclysmic variable AE Aquarii. NuSTAR also discovered 3.76-s pulsations from the transient source SGR J1745-29 recently found by Swift very close to the Galactic Center, clearly identifying the source as a transient magnetar. For magnetar 1E 1841-045, we show that the spectrum is well fit by an absorbed blackbody plus broken power-law model with a hard power-law photon index of ~1.3. This is consistent with previous results by INTEGRAL and RXTE. We also find an interesting double-peaked pulse profile in the 25-35 keV band. For AE Aquarii, we show that the spectrum ca...

  3. Horizontal Branch stars as AmFm/HgMn stars

    CERN Document Server

    Michaud, G

    2008-01-01

    Recent observations and models for horizontal branch stars are briefly described and compared to models for AmFm stars. The limitations of those models are emphasized by a comparison to observations and models for HgMn stars.

  4. In vitro analysis of the susceptibility of HIV-1 subtype A and CRF01_AE integrases to raltegravir.

    Science.gov (United States)

    Bellecave, Pantxika; Malato, Laurent; Calmels, Christina; Reigadas, Sandrine; Parissi, Vincent; Andreola, Marie-Line; Fleury, Hervé

    2014-08-01

    The antiviral efficacy of raltegravir (RAL) has been proven against human immunodeficiency virus type 1 (HIV-1) subtypes B and C but remained to be determined against other subtypes. Therefore, the enzymatic activities as well as RAL resistance of HIV-1 subtype A and CRF01_AE integrases (INs) were investigated. Previously published subtype A and CRF01_AE IN sequences from RAL-naïve patients were aligned to generate consensus sequences for both IN subtypes. Subtype A and CRF01_AE INs encoded by these consensus sequences as well as the corresponding enzymes harbouring the N155H resistance mutation were expressed and purified. Enzymatic activities of subtype A and CRF01_AE INs were analysed with regard to typical 3'-end processing (3'-P) and strand transfer (ST) activities both in the presence and absence of RAL and were compared with subtype B IN as well as with the corresponding INs harbouring the N155H resistance mutation. Subtypes B, A and CRF01_AE INs showed similar 3'-P and ST activities. In the presence of RAL, the three wild-type INs exhibited ST activity IC50 values (50% inhibitory concentrations) of 86.3 ± 32.5, 158.3 ± 99.0 and 100.0 ± 65.7 nM, respectively. Analysis of 3'-P activity in the presence of RAL revealed IC(50) > 10 μM for all three enzymes. The three INs harbouring the N155H mutation presented in vitro low but similar resistance levels to RAL. In conclusion, INs from HIV-1 subtypes B, A and CRF01_AE showed similar responses to RAL in vitro, suggesting the potency of this antiretroviral drug to treat HIV-1 subtype A- and CRF01_AE-infected patients.

  5. Diffusion in phthalocyanine thin film layers: study by AES, EELS, EPES and electrical measurements

    Science.gov (United States)

    Gamoudi, M.; El Beqqali, O.; Benkaddour, M.; Sadoun, M. Al; Guillaud, G.; Miloua, F.; Khelifa, B.; El Ourzaz, L.; Jardin, C.

    1991-12-01

    Diffusion studies are necessary to the feasibility of molecular pn junctions. Electrical and spectroscopic measurements have been done in two superimposed phthalocyanine thin layers: Zinc phthaiocyanine (PcZn) (p material) and Lutetium bisphthalocyanine (PC2Lu) (n material). These measurements are in a good agreement. In spite of the very large dimensions of these molecules, diffusion and doping of PcZn by PC2Lu occur. Moreover, elastic peak electron spectroscopy (EPES) seems more available than Auger electron spectroscopy (AES) to follow the diffusion in such samples. Les études de diffusion sont nécessaires pour utiliser pratiquement les semiconducteurs organiques en particulier pour la réalisation de jonctions pn. Des mesures électriques et spectroscopiques ont été faites sur des couches minces de phtalocyanines superposées : phtalocyanine de Zinc(PcZn) (matériau de type p) et bisphtalocyanine de Lutetium (PC2Lu) (matériau de type n). L'ensemble de ces mesures est en bon accord, la diffusion et le dopage de PcZn par PC2Lu se produisent malgré la taille importante de ces molécules. De plus la spectroscopie de pic élastique (EPES) semble être plus adaptée à ces mesures que la spectroscopie d'électrons Auger (AES) pour suivre la diffusion dans ces échantillons.

  6. AES Cardless Automatic Teller Machine (ATM) Biometric Security System Design Using FPGA Implementation

    Science.gov (United States)

    Ahmad, Nabihah; Rifen, A. Aminurdin M.; Helmy Abd Wahab, Mohd

    2016-11-01

    Automated Teller Machine (ATM) is an electronic banking outlet that allows bank customers to complete a banking transactions without the aid of any bank official or teller. Several problems are associated with the use of ATM card such card cloning, card damaging, card expiring, cast skimming, cost of issuance and maintenance and accessing customer account by third parties. The aim of this project is to give a freedom to the user by changing the card to biometric security system to access the bank account using Advanced Encryption Standard (AES) algorithm. The project is implemented using Field Programmable Gate Array (FPGA) DE2-115 board with Cyclone IV device, fingerprint scanner, and Multi-Touch Liquid Crystal Display (LCD) Second Edition (MTL2) using Very High Speed Integrated Circuit Hardware (VHSIC) Description Language (VHDL). This project used 128-bits AES for recommend the device with the throughput around 19.016Gbps and utilized around 520 slices. This design offers a secure banking transaction with a low rea and high performance and very suited for restricted space environments for small amounts of RAM or ROM where either encryption or decryption is performed.

  7. AES Inspired Hex Symbols Steganography for Anti-Forensic Artifacts on Android Devices

    Directory of Open Access Journals (Sweden)

    Somyia M. Abu Asbeh

    2016-05-01

    Full Text Available Mobile phones technology has become one of the most common and important technologies that started as a communication tool and then evolved into key reservoirs of personal information and smart applications. With this increased level of complications, increased dangers and increased levels of countermeasures and opposing countermeasures have emerged, such as Mobile Forensics and anti-forensics. One of these anti-forensics tools is steganography, which introduced higher levels of complexity and security against hackers’ attacks but simultaneously create obstacles to forensic investigations. In this paper we proposed a new data hiding approach, the AES Inspired Steganography (AIS, which utilizes some AES data encryption concepts while hiding the data using the concept of hex symbols steganography. As the approach is based on the use of multiple encryption steps, the resulting carrier files would be unfathomable without the use of the cipher key agreed upon by the communicating parties. These carrier files can be exchanged amongst android devices and/or computers. Assessments of the proposed approach have proven it to be advantageous over the currently existing steganography approaches in terms of character frequency, security, robustness, length of key, and Compatibility.

  8. Electron stimulated carbon adsorption in ultra high vacuum monitored by Auger Electron Spectroscopy (AES)

    CERN Document Server

    Scheuerlein, C

    2001-01-01

    Electron stimulated carbon adsorption at room temperature (RT) has been studied in the context of radiation induced surface modifications in the vacuum system of particle accelerators. The stimulated carbon adsorption was monitored by AES during continuous irradiation by 2.5 keV electrons and simultaneous exposure of the sample surface to CO, CO2 or CH4. The amount of adsorbed carbon was estimated by measuring the carbon Auger peak intensity as a function of the electron irradiation time. Investigated substrate materials are technical OFE copper and TiZrV non-evaporable getter (NEG) thin film coatings, which are saturated either in air or by CO exposure inside the Auger electron spectrometer. On the copper substrate electron induced carbon adsorption from gas phase CO and CO2 is below the detection limit of AES. During electron irradiation of the non-activated TiZrV getter thin films, electron stimulated carbon adsorption from gas phase molecules is detected when either CO or CO2 is injected, whereas the CH4 ...

  9. AE activity during transient beta drops in high poloidal beta discharges

    Science.gov (United States)

    Huang, J.; Gong, X. Z.; Ren, Q. L.; Ding, S. Y.; Qian, J. P.; Pan, C. K.; Li, G. Q.; Heidbrink, W. W.; Garofalo, A. M.; McClenaghan, J.

    2016-10-01

    Enhanced AE activity has been observed during transient beta drops in high poloidal beta DIII-D discharges with internal transport barriers (ITBs). These drops in beta are believed to be caused by n=1 external kink modes. In some discharges, beta recovers within 200 ms but, in others, beta stays suppressed. A typical discharge has βP 3, qmin 3, and q95 12. The drop in beta affects both fast ions and thermal particles, and a drop is also observed in the density and rotation. The enhanced AE activity follows the instability that causes the beta drop, is largest at the lowest beta, and subsides as beta recovers. MHD stability analysis is planned. A database study of the plasma conditions associated with the collapse will be also presented. Supported in part by the US Department of Energy under DE-FC02-04ER54698, DE-AC05-06OR23100, and by the National Natural Science Foundation of China 11575249, and the National Magnetic Confinement Fusion Program of China No. 2015GB110005.

  10. Hello darkness my old friend: the fading of the nearby TDE ASASSN-14ae

    Science.gov (United States)

    Brown, Jonathan S.; Shappee, Benjamin J.; Holoien, T. W.-S.; Stanek, K. Z.; Kochanek, C. S.; Prieto, J. L.

    2016-11-01

    We present late-time optical spectroscopy taken with the Large Binocular Telescope's Multi-Object Double Spectrograph, an improved All-Sky Automated Survey for SuperNovae pre-discovery non-detection, and late-time Swift observations of the nearby (d = 193 Mpc, z = 0.0436) tidal disruption event (TDE) ASASSN-14ae. Our observations span from ˜20 d before to ˜750 d after discovery. The proximity of ASASSN-14ae allows us to study the optical evolution of the flare and the transition to a host-dominated state with exceptionally high precision. We measure very weak Hα emission 300 d after discovery (LH α ≃ 4 × 1039 erg s-1) and the most stringent upper limit to date on the Hα luminosity ˜750 d after discovery (LH α ≲ 1039 erg s-1), suggesting that the optical emission arising from a TDE can vanish on a time-scale as short as 1 yr. Our results have important implications for both spectroscopic detection of TDE candidates at late times, as well as the nature of TDE host galaxies themselves.

  11. Hello Darkness My Old Friend: The Fading of the Nearby TDE ASASSN-14ae

    CERN Document Server

    Brown, Jonathan S; Holoien, T W -S; Stanek, K Z; Kochanek, C S; Prieto, J L

    2016-01-01

    We present late-time optical spectroscopy taken with the Large Binocular Telescope's Multi-Object Double Spectrograph, an improved ASAS-SN pre-discovery non-detection, and late-time SWIFT observations of the nearby ($d=193$ Mpc, $z=0.0436$) tidal disruption event (TDE) ASASSN-14ae. Our observations span from $\\sim$20 days before to $\\sim$750 days after discovery. The proximity of ASASSN-14ae allows us to study the optical evolution of the flare and the transition to a host dominated state with exceptionally high precision. We measure very weak H$\\alpha$ emission 300 days after discovery ($L_{\\rm H\\alpha} \\simeq 4\\times 10^{39}$ ergs s$^{-1}$) and the most stringent upper limit to date on the H$\\alpha$ luminosity $\\sim$~750 days after discovery ($L_{\\rm H\\alpha} \\lesssim 10^{39}$ ergs s$^{-1}$), suggesting that the optical emission arising from a TDE can vanish on a timescale as short as 1 year. Our results have important implications for both spectroscopic detection of TDE candidates at late times, as well as...

  12. Effect of Deep Cryogenic Treatment on Microstructure and Properties of AE42 Mg Alloy

    Science.gov (United States)

    Bhale, Pranav; Shastri, H.; Mondal, A. K.; Masanta, M.; Kumar, S.

    2016-09-01

    The effect of deep cryogenic treatment (DCT) on microstructure and mechanical properties including corrosion behavior of the squeeze-cast AE42 alloy has been investigated. For comparison, the same has also been studied on the untreated alloy. Both the untreated and deep cryogenic-treated (DCTed) alloys comprised α-Mg and Al4RE phases. Volume fraction of the Al4RE phase in the AE42 alloy reduced gradually following DCT carried out from 4 to 16 h. Ductility and UTS increase significantly with a marginal increase in YS of all the DCTed alloys. The improvement was attributed to the dissolution of the brittle Al4RE phase following DCT. Among the alloys employed, the best tensile properties were obtained for the 16-h DCT alloy due to its lowest content of the brittle Al4RE phase. Creep resistance of the DCTed alloys was lower than that of the untreated alloy owing to the presence of less amount of thermally stable intermetallic Al4RE phase. Wear resistance of the alloy reduces following DCT due to reduced hardness of the DCTed alloys. The untreated alloy exhibits the best corrosion resistance, whereas poor corrosion resistance of the DCTed alloys is attributed to the reduced amount of Al4RE phase that fails to built a corrosion resistance barrier.

  13. High Lightweight Encryption Standard (HLES as an Improvement of 512-Bit AES for Secure Multimedia

    Directory of Open Access Journals (Sweden)

    GUESMIA Seyf Eddine

    2016-01-01

    Full Text Available In today’s scenario, people share information to another people frequently using network. Due to this, more amount of information are so much private but some are less private. Therefore, the attackers or the hackers take the advantage and start attempting to steal the information since 2001. the symmetric encryption algorithm called 512-bit AES provides high level of security, but it's almost be impossible to be used in multimedia transmissions and mobile systems because of the need for more design area that effect in the use of large memory space in each round and the big encryption time that it takes. This paper presents an improvement of 512-bit AES algorithm with efficient utilization of resources such as processor and memory space. The proposed approach resists the linear and differential encrypt analysis and provides high security level using a 512-bit size of key block and data block and ameliorates the performance by minimizing the use of memory space and time encryption to be able to work in specific characteristics of resource-limited systems. The experimental results on several data (text, image, sound, video show that the used memory space is reduced to quarter, and the encryption time is reduced almost to the half. Therefore, the adopted method is very effective for encryption of multimedia data.

  14. Hot and cool water in Herbig Ae protoplanetary disks. A challenge for Herschel

    CERN Document Server

    Woitke, Peter; Kamp, Inga; Hogerheijde, Michiel R

    2009-01-01

    The spatial origin and detectability of rotational H2O emission lines from Herbig Ae type protoplanetary disks beyond 70 micron is discussed. We use the recently developed disk code ProDiMo to calculate the thermo-chemical structure of a Herbig Ae type disk and apply the non-LTE line radiative transfer code Ratran to predict water line profiles and intensity maps. The model shows three spatially distinct regions in the disk where water concentrations are high, related to different chemical pathways to form the water: (1) a big water reservoir in the deep midplane behind the inner rim, (2) a belt of cold water around the distant icy midplane beyond the snow-line r>20AU, and (3) a layer of irradiated hot water at high altitudes z/r=0.1...0.3, extending from about 1AU to 30AU, where the kinetic gas temperature ranges from 200K to 1500K. Although region 3 contains only little amounts of water vapour (~3x10^-5 M_Earth), we find this warm layer to be almost entirely responsible for the rotational water emission lin...

  15. Satellite Image Security Improvement by Combining DWT-DCT Watermarking and AES Encryption

    Directory of Open Access Journals (Sweden)

    Naida.H.Nazmudeen

    2014-06-01

    Full Text Available With the large-scale research in space sciences and technologies, there is a great demand of satellite image security system for providing secure storage and transmission of satellite images. As the demand to protect the sensitive and valuable data from satellites has increased and hence proposed a new method for satellite image security by combining DWT-DCT watermarking and AES encryption. Watermarking techniques developed for multimedia data cannot be directly applied to the satellite images because here the analytic integrity of the data, rather than perceptual quality, is of primary importance. To improve performance, combine discrete wavelet transform (DWT with another equally powerful transform; the discrete cosine transform (DCT. The combined DWT-DCT watermarking algorithm’s imperceptibility was better than the performance of the DWT approach. Modified decision based unsymmetrical trimmed median filter (MDBUTMF algorithm is proposed for the restoration of satellite images that are highly corrupted by salt and pepper noise. Satellite images desire not only the watermarking for copyright protection but also encryption during storage and transmission for preventing information leakage. Hence this paper investigates the security and performance level of joint DWT-DCT watermarking and Advanced Encryption Standard (AES for satellite imagery. Theoretical analysis can be done by calculating PSNR and MSE. The experimental results demonstrate the efficiency of the proposed scheme, which fulfils the strict requirements concerning alterations of satellite images.

  16. Research on tensile fracture process of polyester woven fabric based on AE technique and HHT

    Directory of Open Access Journals (Sweden)

    Yajing XUE

    2016-10-01

    Full Text Available In order to obtain and study time-frequency characteristics of fabric tensile failure modes, four kinds of fabrics is woven with changing different fabric organizational structures and weft densities, dynamic audio signals for different fabrics in tensile failure process is collected with the aid of self-built acoustic emission detection system on the conventional fabric tensile tester, and the collected signal is analyzed and processed by using Matlab software to run a program compiled based on Hilbert Huang transform. The results show that AE signal curve is completely corresponding to tensile load-displacement curve in fabric tensile process, and characterizations of three failure modes about structure change, yarn deformation, and yarn fracture can be clearly distinguished. The characteristic frequency of four kinds of fabrics in structure change stage is the same as 100 Hz, which can be derived from the same source (orthogonal friction of yarns, and has nothing to do with the fabric organizational structure or density. The structure change stage has something to do with yarn strength utilization in such aspects as the AE signals characteristics of duration, amplitude, energy, and so on.

  17. Heavy metals assessment in Oum Er Rbia bassin using WD-XRF and ICP-AES

    Science.gov (United States)

    Zahry, F.; Labraimi, M.; Bilal, E.; Gruffat, J. J.; Moutte, J.; Garcia, D.; Bounakhla, M.

    2003-05-01

    The analysis of water, suspended particulate matter (SPM) and sediment collected from Oum er Rbia Moroccan basin for the content of six elements has been performed utilizing ICP-AES and WD-XRF methods. Sediment have been analyzed by WD-XRF; Water and MPS by ICP-AES. The detection limits are sufficient for most of the elements to be determined. Results were assessed for the accuracy by the analysis of a multi-elemental standards. The results for most of the elements obtained were accurate to about 2 15%. The objective of the analysis were to determine the geochemical areas on this bassin, to explain the mechanisms of sediment transport and nevertheless, to assess the pollution of the bassin by heavy metals generated by human activities. This work interests only the last aspect. It has done one 30samples of water and SPM, and about 80 sediments. Samples were collected along the river, between its source in meddle Atlas and the Atlantic ocean at Azemour city. The results obtained on the basin were normalized to the international norms.

  18. A Study of the X-Ray Emission of Magnetic Cataclysmic Variable Ae Aquarii

    CERN Document Server

    Choi, C S; Agrawal, P C; Choi, Chul-Sung; Dotani, Tadayasu

    1999-01-01

    We report results from analysis of the X-ray observations of AE Aqr, made with Ginga in June 1988 and with ASCA in October 1995. Pulsations are detected clearly with a sinusoidal pulse profile with periods of $33.076\\pm0.001$ s (Ginga) and $33.077\\pm0.003$ s (ASCA)\\@. The pulse amplitude is relatively small and the modulated flux remains nearly constant despite a factor of 3 change in the average flux during the flare. We reproduce the time-averaged spectrum in the 0.4 -- 10 keV energy band by a thermal emission model with a combination of two different temperatures: kT$_1 = 0.68^{+0.01}_{-0.02}$ keV and kT$_2 = 2.9^{+0.3}_{-0.2}$ keV\\@. There is no significant difference between the quiescent and flare energy spectra, although a hint of spectral hardening is recognized during the flare. We interpret these observational results with a model in which AE Aqr is in a propeller stage. Based on this propeller scenario, we suggest that the X-ray emission is originated from magnetospheric radiation.

  19. HOT GAS LINES IN T TAURI STARS

    Energy Technology Data Exchange (ETDEWEB)

    Ardila, David R. [NASA Herschel Science Center, California Institute of Technology, MC 100-22, Pasadena, CA 91125 (United States); Herczeg, Gregory J. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Gregory, Scott G.; Hillenbrand, Lynne A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Ingleby, Laura; Bergin, Edwin; Bethell, Thomas; Calvet, Nuria [Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States); France, Kevin; Brown, Alexander [Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309-0389 (United States); Edwards, Suzan [Department of Astronomy, Smith College, Northampton, MA 01063 (United States); Johns-Krull, Christopher [Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States); Linsky, Jeffrey L. [JILA, University of Colorado and NIST, 440 UCB Boulder, CO 80309-0440 (United States); Yang, Hao [Institute for Astrophysics, Central China Normal University, Wuhan 430079 (China); Valenti, Jeff A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Abgrall, Herve [LUTH and UMR 8102 du CNRS, Observatoire de Paris, Section de Meudon, Place J. Janssen, F-92195 Meudon (France); Alexander, Richard D. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Brown, Joanna M.; Espaillat, Catherine [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 78, Cambridge, MA 02138 (United States); Hussain, Gaitee, E-mail: ardila@ipac.caltech.edu [ESO, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Muenchen (Germany); and others

    2013-07-01

    For Classical T Tauri Stars (CTTSs), the resonance doublets of N V, Si IV, and C IV, as well as the He II 1640 A line, trace hot gas flows and act as diagnostics of the accretion process. In this paper we assemble a large high-resolution, high-sensitivity data set of these lines in CTTSs and Weak T Tauri Stars (WTTSs). The sample comprises 35 stars: 1 Herbig Ae star, 28 CTTSs, and 6 WTTSs. We find that the C IV, Si IV, and N V lines in CTTSs all have similar shapes. We decompose the C IV and He II lines into broad and narrow Gaussian components (BC and NC). The most common (50%) C IV line morphology in CTTSs is that of a low-velocity NC together with a redshifted BC. For CTTSs, a strong BC is the result of the accretion process. The contribution fraction of the NC to the C IV line flux in CTTSs increases with accretion rate, from {approx}20% to up to {approx}80%. The velocity centroids of the BCs and NCs are such that V{sub BC} {approx}> 4 V{sub NC}, consistent with the predictions of the accretion shock model, in at most 12 out of 22 CTTSs. We do not find evidence of the post-shock becoming buried in the stellar photosphere due to the pressure of the accretion flow. The He II CTTSs lines are generally symmetric and narrow, with FWHM and redshifts comparable to those of WTTSs. They are less redshifted than the CTTSs C IV lines, by {approx}10 km s{sup -1}. The amount of flux in the BC of the He II line is small compared to that of the C IV line, and we show that this is consistent with models of the pre-shock column emission. Overall, the observations are consistent with the presence of multiple accretion columns with different densities or with accretion models that predict a slow-moving, low-density region in the periphery of the accretion column. For HN Tau A and RW Aur A, most of the C IV line is blueshifted suggesting that the C IV emission is produced by shocks within outflow jets. In our sample, the Herbig Ae star DX Cha is the only object for which we find a

  20. Structure of Herbig AeBe disks at the milliarcsecond scale A statistical survey in the H band using PIONIER-VLTI

    CERN Document Server

    Lazareff, B; Kluska, J; Bouquin, J -B Le; Benisty, M; Malbet, F; Koen, C; Pinte, C; Thi, W -F; Absil, O; Baron, F; Delboulbé, A; Duvert, G; Isella, A; Jocou, L; Juhasz, A; Kraus, S; Lachaume, R; Ménard, F; Millan-Gabet, R; Monnier, J D; Moulin, T; Perraut, K; Rochat, S; Soulez, F; Tallon, M; Thiébaut, E; Traub, W; Zins, G

    2016-01-01

    Context. It is now generally accepted that the near-infrared excess of Herbig AeBe stars originates in the dust of a circumstellar disk. Aims. The aims of this article are to infer the radial and vertical structure of these disks at scales of order one au, and the properties of the dust grains. Methods. The program objects (51 in total) were observed with the H-band (1.6micron) PIONIER/VLTI interferometer. The largest baselines allowed us to resolve (at least partially) structures of a few tenths of an au at typical distances of a few hundred parsecs. Dedicated UBVRIJHK photometric measurements were also obtained. Spectral and 2D geometrical parameters are extracted via fits of a few simple models: ellipsoids and broadened rings with azimuthal modulation. Model bias is mitigated by parallel fits of physical disk models. Sample statistics were evaluated against similar statistics for the physical disk models to infer properties of the sample objects as a group. Results. We find that dust at the inner rim of th...

  1. Star Trek in the Schools

    Science.gov (United States)

    Journal of Aerospace Education, 1977

    1977-01-01

    Describes specific educational programs for using the Star Trek TV program from kindergarten through college. For each grade level lesson plans, ideas for incorporating Star Trek into future classes, and reports of specific programs utilizing Star Trek are provided. (SL)

  2. Stars and Flowers, Flowers and Stars

    Science.gov (United States)

    Minti, Hari

    2012-12-01

    The author, a graduated from the Bucharest University (1964), actually living and working in Israel, concerns his book to variable stars and flowers, two domains of his interest. The analogies includes double stars, eclipsing double stars, eclipses, Big Bang. The book contains 34 chapters, each of which concerns various relations between astronomy and other sciences and pseudosciences such as Psychology, Religion, Geology, Computers and Astrology (to which the author is not an adherent). A special part of the book is dedicated to archeoastronomy and ethnoastronomy, as well as to history of astronomy. Between the main points of interest of these parts: ancient sanctuaries in Sarmizegetusa (Dacia), Stone Henge(UK) and other. The last chapter of the book is dedicated to flowers. The book is richly illustrated. It is designed for a wide circle of readers.

  3. PAHs and star formation

    NARCIS (Netherlands)

    Tielens, AGGM; Peeters, E; Bakes, ELO; Spoon, HWW; Hony, S; Johnstone, D; Adams, FC; Lin, DNC; Neufeld, DA; Ostriker, EC

    2004-01-01

    Strong IR emission features at 3.3, 6.2, 7.7, 8.6, and 11.2 mum are a common characteristic of regions of massive star formation. These features are carried by large (similar to 50 C-atom) Polycyclic Aromatic Hydrocarbon molecules which are pumped by the strong FUV photon flux from these stars. Thes

  4. Observing Double Stars

    Science.gov (United States)

    Genet, Russell M.; Fulton, B. J.; Bianco, Federica B.; Martinez, John; Baxter, John; Brewer, Mark; Carro, Joseph; Collins, Sarah; Estrada, Chris; Johnson, Jolyon; Salam, Akash; Wallen, Vera; Warren, Naomi; Smith, Thomas C.; Armstrong, James D.; McGaughey, Steve; Pye, John; Mohanan, Kakkala; Church, Rebecca

    2012-05-01

    Double stars have been systematically observed since William Herschel initiated his program in 1779. In 1803 he reported that, to his surprise, many of the systems he had been observing for a quarter century were gravitationally bound binary stars. In 1830 the first binary orbital solution was obtained, leading eventually to the determination of stellar masses. Double star observations have been a prolific field, with observations and discoveries - often made by students and amateurs - routinely published in a number of specialized journals such as the Journal of Double Star Observations. All published double star observations from Herschel's to the present have been incorporated in the Washington Double Star Catalog. In addition to reviewing the history of visual double stars, we discuss four observational technologies and illustrate these with our own observational results from both California and Hawaii on telescopes ranging from small SCTs to the 2-meter Faulkes Telescope North on Haleakala. Two of these technologies are visual observations aimed primarily at published "hands-on" student science education, and CCD observations of both bright and very faint doubles. The other two are recent technologies that have launched a double star renaissance. These are lucky imaging and speckle interferometry, both of which can use electron-multiplying CCD cameras to allow short (30 ms or less) exposures that are read out at high speed with very low noise. Analysis of thousands of high speed exposures allows normal seeing limitations to be overcome so very close doubles can be accurately measured.

  5. The four serotypes of dengue recognize the same putative receptors in Aedes aegypti midgut and Ae. albopictus cells

    Directory of Open Access Journals (Sweden)

    Camacho-Nuez Minerva

    2006-10-01

    Full Text Available Abstract Background Dengue viruses (DENV attach to the host cell surface and subsequently enter the cell by receptor-mediated endocytosis. Several primary and low affinity co-receptors for this flavivirus have been identified. However, the presence of these binding molecules on the cell surface does not necessarily render the cell susceptible to infection. Determination of which of them serve as bona fide receptors for this virus in the vector may be relevant to treating DENV infection and in designing control strategies. Results (1 Overlay protein binding assay showed two proteins with molecular masses of 80 and 67 kDa (R80 and R67. (2 Specific antibodies against these two proteins inhibited cell binding and infection. (3 Both proteins were bound by all four serotypes of dengue virus. (4 R80 and R67 were purified by affinity chromatography from Ae. aegypti mosquito midguts and from Ae albopictus C6/36 cells. (5 In addition, a protein with molecular mass of 57 kDa was purified by affinity chromatography from the midgut extracts. (6 R80 and R67 from radiolabeled surface membrane proteins of C6/36 cells were immunoprecipitated by antibodies against Ae. aegypti midgut. Conclusion Our results strongly suggest that R67 and R80 are receptors for the four serotypes of dengue virus in the midgut cells of Ae. aegypti and in C6/36 Ae. albopictus cells.

  6. Ages of young stars

    CERN Document Server

    Soderblom, David R; Jeffries, Rob D; Mamajek, Eric E; Naylor, Tim

    2013-01-01

    Determining the sequence of events in the formation of stars and planetary systems and their time-scales is essential for understanding those processes, yet establishing ages is fundamentally difficult because we lack direct indicators. In this review we discuss the age challenge for young stars, specifically those less than ~100 Myr old. Most age determination methods that we discuss are primarily applicable to groups of stars but can be used to estimate the age of individual objects. A reliable age scale is established above 20 Myr from measurement of the Lithium Depletion Boundary (LDB) in young clusters, and consistency is shown between these ages and those from the upper main sequence and the main sequence turn-off -- if modest core convection and rotation is included in the models of higher-mass stars. Other available methods for age estimation include the kinematics of young groups, placing stars in Hertzsprung-Russell diagrams, pulsations and seismology, surface gravity measurement, rotation and activ...

  7. Gaia and Variable Stars

    CERN Document Server

    Udalski, A; Skowron, D M; Skowron, J; Pietrukowicz, P; Mróz, P; Poleski, R; Szymański, M K; Kozłowski, S; Wyrzykowski, Ł; Ulaczyk, K; Pawlak, M

    2016-01-01

    We present a comparison of the Gaia DR1 samples of pulsating variable stars - Cepheids and RR Lyrae type - with the OGLE Collection of Variable Stars aiming at the characterization of the Gaia mission performance in the stellar variability domain. Out of 575 Cepheids and 2322 RR Lyrae candidates from the Gaia DR1 samples located in the OGLE footprint in the sky, 559 Cepheids and 2302 RR Lyrae stars are genuine pulsators of these types. The number of misclassified stars is low indicating reliable performance of the Gaia data pipeline. The completeness of the Gaia DR1 samples of Cepheids and RR Lyrae stars is at the level of 60-75% as compared to the OGLE Collection dataset. This level of completeness is moderate and may limit the applicability of the Gaia data in many projects.

  8. Revised Anatomy of Stars

    CERN Document Server

    Dubin, M; Dubin, Maurice; Soberman, Robert K.

    1997-01-01

    Stars accrete near invisible hydrogen dominated agglomerates. This population, the `dark matter,' effects the nature of stars. Measurements show plasma streams impacting Earth, planets, Sun and stars. This mass-energy source contradicts nebula collapse model for stars. The visual derived model, to which later discoveries (e.g., fusion) were appended, is confounded and contradicted by new observations. Discovery of a quantity of beryllium 7 (53 day half-life) in the Earth's upper atmosphere, fusion produced, hence from the solar outer zone, proves core fusion wrong. Magnetically pinched plasmas from aggregates impact stars at hundreds of km/s, create impulsive conditions for nuclear explosions below the surface. Disks with planets aid cluster capture. Planets modulate the influx varying fusion, hence luminosity (e.g., solar cycle). This population, with no assumptions or ad hoc physics, explains mysterious phenomena, e.g., luminosity/wind variation, sunspots, high temperature corona, CMEs, etc. Standard explan...

  9. Mira Symbiotic Stars

    Institute of Scientific and Technical Information of China (English)

    Guo-Liang Lü; Chun-Hua Zhu; Zhan-Wen Han

    2007-01-01

    We have carried out a detailed study of Mira symbiotic stars by means of a population synthesis code. We estimate the number of Mira symbiotic stars in the Galaxy as 1700 - 3100 and the Galactic occurrence rate of Mira symbiotic novae as from ~ 0.9 to 6.0 yr-1,depending on the model assumptions. The distributions of the orbital periods, the masses of the components, mass-loss rates of cool components, mass-accretion rates of hot components and Mira pulsation periods in Mira symbiotic stars are simulated. By a comparison of the number ratio of Mira symbiotic stars to all symbiotic stars, we find the model with the stellar wind model of Winters et al. to be reasonable.

  10. Producing Runaway Stars

    Science.gov (United States)

    Kohler, Susanna

    2016-07-01

    How are the hypervelocity stars weve observed in our galaxy produced? A recent study suggests that these escapees could be accelerated by a massive black hole in the center of the Large Magellanic Cloud.A Black Hole SlingshotSince their discovery in 2005, weve observed dozens of candidate hypervelocity stars stars whose velocity in the rest frame of our galaxy exceeds the local escape velocity of the Milky Way. These stars present a huge puzzle: how did they attain these enormous velocities?One potential explanation is known as the Hills mechanism. In this process, a stellar binary is disrupted by a close encounter with a massive black hole (like those thought to reside at the center of every galaxy). One member of the binary is flung out of the system as a result of the close encounter, potentially reaching very large velocities.A star-forming region known as LHA 120-N 11, located within the LMC. Some binary star systems within the LMC might experience close encounters with a possible massive black hole at the LMCs center. [ESA/NASA/Hubble]Blame the LMC?Usually, discussions of the Hills mechanism assume that Sagittarius A*, the supermassive black hole at the center of the Milky Way, is the object guilty of accelerating the hypervelocity stars weve observed. But what if the culprit isnt Sgr A*, but a massive black hole at the center of the Large Magellanic Cloud (LMC), one of the Milky Ways satellite galaxies?Though we dont yet have evidence of a massive black hole at the center of the LMC, the dwarf galaxy is large enough to potentially host one as large as 100,000 solar masses. Assuming that it does, two scientists at the University of Cambridge, Douglas Boubert and Wyn Evans, have now modeled how this black hole might tear apart binary star systems and fling hypervelocity stars around the Milky Way.Models for AccelerationBoubert and Evans determined that the LMCs hypothetical black hole could easily eject stars at ~100 km/s, which is the escape velocity of the

  11. The Carbon Star Phenomenon

    Science.gov (United States)

    Wing, Robert F.

    2000-06-01

    The atmospheres of many stars have chemical compositions that are significantly different from that of the interstellar medium from which they are formed. This symposium considered all kinds of late-type stars showing altered compositions, the carbon stars being simply the best-known of these. All stages of stellar evolution from the main sequence to the ejection of a planetary nebula were considered, with emphasis on the changes that occur on the asymptotic giant branch. The spectroscopic properties of the photospheres and circumstellar envelopes of chemically-peculiar red giant stars, their origins via single-star evolution or mass transfer in binary systems, and the methods currently used to study them were all discussed in detail. This volume includes the full texts of papers given orally at the symposium and abstracts of the posters. Link: http://www.wkap.nl/book.htm/0-7923-6347-7

  12. Neutron Stars and Pulsars

    CERN Document Server

    Becker, Werner

    2009-01-01

    Neutron stars are the most compact astronomical objects in the universe which are accessible by direct observation. Studying neutron stars means studying physics in regimes unattainable in any terrestrial laboratory. Understanding their observed complex phenomena requires a wide range of scientific disciplines, including the nuclear and condensed matter physics of very dense matter in neutron star interiors, plasma physics and quantum electrodynamics of magnetospheres, and the relativistic magneto-hydrodynamics of electron-positron pulsar winds interacting with some ambient medium. Not to mention the test bed neutron stars provide for general relativity theories, and their importance as potential sources of gravitational waves. It is this variety of disciplines which, among others, makes neutron star research so fascinating, not only for those who have been working in the field for many years but also for students and young scientists. The aim of this book is to serve as a reference work which not only review...

  13. Monte Carlo simulation of star/linear and star/star blends with chemically identical monomers

    Energy Technology Data Exchange (ETDEWEB)

    Theodorakis, P E [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Avgeropoulos, A [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Freire, J J [Departamento de Ciencias y Tecnicas FisicoquImicas, Universidad Nacional de Educacion a Distancia, Facultad de Ciencias, Senda del Rey 9, 28040 Madrid (Spain); Kosmas, M [Department of Chemistry, University of Ioannina, 45110 Ioannina (Greece); Vlahos, C [Department of Chemistry, University of Ioannina, 45110 Ioannina (Greece)

    2007-11-21

    The effects of chain size and architectural asymmetry on the miscibility of blends with chemically identical monomers, differing only in their molecular weight and architecture, are studied via Monte Carlo simulation by using the bond fluctuation model. Namely, we consider blends composed of linear/linear, star/linear and star/star chains. We found that linear/linear blends are more miscible than the corresponding star/star mixtures. In star/linear blends, the increase in the volume fraction of the star chains increases the miscibility. For both star/linear and star/star blends, the miscibility decreases with the increase in star functionality. When we increase the molecular weight of linear chains of star/linear mixtures the miscibility decreases. Our findings are compared with recent analytical and experimental results.

  14. Magnetic Fields of Be Stars: Preliminary Results from a Hybrid Analysis of the MiMeS Sample

    Science.gov (United States)

    Wade, G. A.; Petit, V.; Grunhut, J. H.; Neiner, C.; MiMeS Collaboration

    2016-11-01

    In the context of the MiMeS survey of magnetism in massive stars, 85 classical Be stars were observed in circular polarization with the aim of detecting magnetic fields at their surfaces. No direct evidence of such fields is found, in contrast to the significant rate of detection (5-10%) in non-Be B-type stars. In this paper we describe the sample properties, the methodology and the data quality. We describe a novel method, previously applied to Herbig Ae/Be stars, that allows us to infer upper limits on organized (dipolar) magnetic fields present in the photospheres of our targets. We review the characteristics and robustness of this null result, and discuss its implications.

  15. Catch a Star!

    Science.gov (United States)

    2006-11-01

    ESO and the European Association for Astronomy Education are launching today the 2007 edition of 'Catch a Star!', their international astronomy competition for school students. Now in its fifth year, the competition offers students the chance to win a once-in-a-lifetime trip to ESO's flagship observatory in Chile, as well as many other prizes. Students are invited to 'become astronomers' and embark on a journey to explore the Universe. ESO PR Photo 42/06 The competition includes separate categories - 'Catch a Star Researchers' and 'Catch a Star Adventurers' - to ensure that every student, whatever their level, has the chance to enter and win exciting prizes. For the artistically minded, 'Catch a Star!' also includes an artwork competition, 'Catch a Star Artists'. "'Catch a Star!' offers a unique opportunity for students to learn more about astronomy and about the methods scientists use to discover new things about the Universe", said Douglas Pierce-Price, Education Officer at ESO. In teams, students choose an astronomical topic to study and produce an in-depth report. An important part of the project for 'Catch a Star Researchers' is to think about how ESO's telescopes or a telescope of the future can contribute to their investigations of the subject. As well as the top prize - a trip to one of ESO's observatory sites in Chile - visits to observatories in Germany, Austria and Spain, and many other prizes are also available to be won. 'Catch a Star Researchers' winners will be chosen by an international jury, and 'Catch a Star Adventurers' will be awarded further prizes by lottery. Entries for 'Catch a Star Artists' will be displayed on the web and winners chosen with the help of a public online vote. The first editions of 'Catch a Star!' have attracted several hundred entries from more than 25 countries worldwide. Previous winning entries have included "Star clusters and the structure of the Milky Way" (Budapest, Hungary), "Vega" (Acqui Terme, Italy) and "Venus

  16. Hot Subluminous Stars

    Science.gov (United States)

    Heber, U.

    2016-08-01

    Hot subluminous stars of spectral type B and O are core helium-burning stars at the blue end of the horizontal branch or have evolved even beyond that stage. Most hot subdwarf stars are chemically highly peculiar and provide a laboratory to study diffusion processes that cause these anomalies. The most obvious anomaly lies with helium, which may be a trace element in the atmosphere of some stars (sdB, sdO) while it may be the dominant species in others (He-sdB, He-sdO). Strikingly, the distribution in the Hertzsprung-Russell diagram of He-rich versus He-poor hot subdwarf stars of the globular clusters ω Cen and NGC 2808 differ from that of their field counterparts. The metal-abundance patterns of hot subdwarfs are typically characterized by strong deficiencies of some lighter elements as well as large enrichments of heavy elements. A large fraction of sdB stars are found in close binaries with white dwarf or very low-mass main sequence companions, which must have gone through a common-envelope (CE) phase of evolution. Because the binaries are detached they provide a clean-cut laboratory to study this important but yet poorly understood phase of stellar evolution. Hot subdwarf binaries with sufficiently massive white dwarf companions are viable candidate progenitors of type Ia supernovae both in the double degenerate as well as in the single degenerate scenario as helium donors for double detonation supernovae. The hyper-velocity He-sdO star US 708 may be the surviving donor of such a double detonation supernova. Substellar companions to sdB stars have also been found. For HW Vir systems the companion mass distribution extends from the stellar into the brown dwarf regime. A giant planet to the acoustic-mode pulsator V391 Peg was the first discovery of a planet that survived the red giant evolution of its host star. Evidence for Earth-size planets to two pulsating sdB stars have been reported and circumbinary giant planets or brown dwarfs have been found around HW

  17. Application of Glow Discharge Aes for Investigation of Metal Ions and Water in Biology and Medicine

    CERN Document Server

    Bregadze, Vasil G; Tsakadze, Ketevan J

    2007-01-01

    AES VHF inductively coupled plasmatron may be applied to wide range of studies. It enables rapid microanalysis of various solutions including biological objects and peripheral blood serum. In addition, it may be used for investigation of water desorption from solid bodies and for determination of energetic metal-macromolecule complexes. Study of hydration energy and hydration number by kinetic curves of water glow discharge atomic spectral analysis of hydrogen (GD EAS analysis of hydrogen) desorption from Na-DNA humidified fibers allowed to reveal that structural and conformational changes in activation energy of hydrated water molecules increases by 0.65kcal/Mole of water. The developed method of analysis of elements in solutions containing high concentrations of organic materials allows systematic study of practically healthy persons and reveals risk factors for several diseases. Microelemental content of blood serum fractions showed that amount of not bounded with ceruloplasmin copper was three times more ...

  18. [Qualitative and quantitative analysis of various elements in chromite ore by ICP-AES].

    Science.gov (United States)

    Zhang, Yang; Zheng, Shi-li; Wang, Xiao-hui; Xu, Hong-bin; Zhang, Yi

    2010-01-01

    Kind of the elements in chromite ore was firstly determined by ICP-AES. Twenty nine elements, such as Cr, Fe, Al, Mg, Zn, Ca and Ni, were contained in the chromite sample based on the qualitative analysis. Then the contents of main elements Cr, Fe, Al, Mg, Ca, T, Si, Mn and V were measured. The chromite samples processing procedures have two steps, the first is decomposition by nitrate carbonate and sodium tetraborate at 950 degrees C for 30 min, then leaching by dilute hydrochloric acid at 80 degrees C for 10 min. The method showed satisfactory precision and accuracy with the RSDs between 0.48% and 2.05% and the recovery rates between 90.5% and 111.3%.

  19. Studies on injector pump-ultrasonic nebulizer feeding sample system for MPT-AES

    Institute of Scientific and Technical Information of China (English)

    Feng Guodong; Hang Songbai; Yu Aimin

    2006-01-01

    The feeding-sample system used by microwave plasma torch atomic emission spectroscopy(MPT-AES)is the pneumatic nebulization system;its efficiency,however,is not good.A newly built injector pump-ultrasonic nebulizer combination feeding-sample system has been designed.Its performance was tested and compared with that of the pneumatic nebulization system.It can be concluded that the newly built feeding-sample system can increase the spectral line intensity by about two to three times and decrease the detection limit by about 2 to 10 times.Moreover,this newly built system can reduce the time taken washing the sample cell from 30 rain or so to about 10 rain.

  20. Can Pearlite form Outside of the Hultgren Extrapolation of the Ae3 and Acm Phase Boundaries?

    Science.gov (United States)

    Aranda, M. M.; Rementeria, R.; Capdevila, C.; Hackenberg, R. E.

    2016-02-01

    It is usually assumed that ferrous pearlite can form only when the average austenite carbon concentration C 0 lies between the extrapolated Ae3 ( γ/ α) and Acm ( γ/ θ) phase boundaries (the "Hultgren extrapolation"). This "mutual supersaturation" criterion for cooperative lamellar nucleation and growth is critically examined from a historical perspective and in light of recent experiments on coarse-grained hypoeutectoid steels which show pearlite formation outside the Hultgren extrapolation. This criterion, at least as interpreted in terms of the average austenite composition, is shown to be unnecessarily restrictive. The carbon fluxes evaluated from Brandt's solution are sufficient to allow pearlite growth both inside and outside the Hultgren Extrapolation. As for the feasibility of the nucleation events leading to pearlite, the only criterion is that there are some local regions of austenite inside the Hultgren Extrapolation, even if the average austenite composition is outside.

  1. Determination of Metal Contents of Various Fibers Used in Textile Industry by MP-AES

    Directory of Open Access Journals (Sweden)

    Şana Sungur

    2015-01-01

    Full Text Available The concentrations of metals (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Tl, and Zn in various textile fibers (cotton, acrylic, polyester, nylon, viscose, and polypropylene of different colors (red, white, green, blue, yellow, orange, black, brown, purple, pink, navy, burgundy, beige, and grey were determined by microwave plasma-atomic emission spectroscopy (MP-AES. Textile fibers were collected from the various textile plants in Gaziantep-Kahramanmaraş, Turkey. Heavy metals concentrations in all examined textile fibers after wet digestion were found to be high, whereas in the artificial sweat extract they were low. The only lead concentrations in textile fibers analyzed after extraction in the artificial sweat solution were found higher than limit values given by Oeko-Tex.

  2. The surface cleanliness of 316 L + N stainless steel studied by SIMS and AES

    CERN Document Server

    Mathewson, A G

    1974-01-01

    Some cleaning methods for 316 L+N stainless steel including solvent cleaning, high temperature treatment in vacuo and gas discharge cleaning have been studied by SIMS and AES with a view to providing a clean vacuum chamber surface with low gas desorption under ion bombardment. After solvent cleaning the main surface contaminant was found to be C and its associated compounds. Laboratory investigations on small samples of stainless steel showed that clean surfaces could be obtained by heating in vacuo to 800 degrees C followed by exposure to air and by argon or argon/10% oxygen discharge cleaning. Due to a cross contamination within the vacuum system, the 800 degrees C treated chamber gave positive desorption coefficients under ion bombardment. The pure argon discharge cleaned chambers proved stable giving negative desorption coefficients up to 2200 eV ion energy even after several weeks storage discharge treatment and installation. (10 refs).

  3. Dynamic inhomogeneous S-Boxes in AES: a novel countermeasure against power analysis attacks

    Institute of Scientific and Technical Information of China (English)

    Chen Yicheng; Zou Xuecheng; Liu Zhenglin; Han Yu; Zheng Zhaoxia

    2008-01-01

    Substitution boxes (S-Boxes) in advanced encryption standard (AES) are vulnerable to attacks by power analysis. The general S-Boxes masking schemes in circuit level need to adjust the design flow and library databases. The masking strategies in algorithm level view each S-Box as an independent module and mask them respectively, which are costly in size and power for non-linear characteristic of S-Boxes. The new method uses dynamic inhomogeneous S-Boxes instead of traditional homogeneous S-Boxes, and arranges the S-Boxes randomly. So the power and data path delay of substitution unit become unpredictable. The experimental results demonstrate that this scheme takes advantages of the circuit characteristics of various S-Box implementations to eliminate the correlation between crypto operation and power. It needs less extra circuits and suits resource constrained applications.

  4. Asphodosides A-E, anti-MRSA metabolites from Asphodelus microcarpus.

    Science.gov (United States)

    Ghoneim, Mohammed M; Elokely, Khaled M; El-Hela, Atef A; Mohammad, Abd-Elsalam I; Jacob, Melissa; Radwan, Mohamed M; Doerksen, Robert J; Cutler, Stephen J; Ross, Samir A

    2014-09-01

    Bioassay guided fractionation of the ethanolic extract of Asphodelus microcarpus Salzm. et Viv. (Xanthorrhoeaceae or Asphodelaceae) resulted in isolation of five compounds identified as asphodosides A-E (1-5). Compounds 2-4 showed activity against methicillin resistant Staphylococcus aureus (MRSA) with IC50 values of 1.62, 7.0 and 9.0μg/mL, respectively. They also exhibited activity against Staphylococcus aureus (non-MRSA) with IC50 values of 1.0, 3.4 and 2.2μg/mL, respectively. The structure elucidation of isolated metabolites was carried out using spectroscopic data (1D and 2D NMR), optical rotation and both experimental and calculated electronic circular dichroism (ECD).

  5. Dense Axion Stars

    CERN Document Server

    Braaten, Eric; Zhang, Hong

    2015-01-01

    If the dark matter consists of axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound Bose-Einstein condensates of axions. In the previously known axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure.If the axion mass energy is $mc^2= 10^{-4}$ eV, these dilute axion stars have a maximum mass of about $10^{-14} M_\\odot$. We point out that there are also dense axion stars in which gravity is balanced by the mean-field pressure of the axion condensate. We study axion stars using the leading term in a systematically improvable approximation to the effective potential of the nonrelativistic effective field theory for axions. Using the Thomas-Fermi approximation in which the kinetic pressure is neglected, we find a sequence of new branches of axion stars in which gravity is balanced by the mean-field interaction energy of the axion condensate. If $mc^2 = 10^{-4}$ eV, the first branch of these dense axion stars has mas...

  6. Dense Axion Stars

    Science.gov (United States)

    Braaten, Eric; Mohapatra, Abhishek; Zhang, Hong

    2016-09-01

    If the dark matter particles are axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound systems of axions. In the previously known solutions for axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure. The mass of these dilute axion stars cannot exceed a critical mass, which is about 10-14M⊙ if the axion mass is 10-4 eV . We study axion stars using a simple approximation to the effective potential of the nonrelativistic effective field theory for axions. We find a new branch of dense axion stars in which gravity is balanced by the mean-field pressure of the axion Bose-Einstein condensate. The mass on this branch ranges from about 10-20M⊙ to about M⊙ . If a dilute axion star with the critical mass accretes additional axions and collapses, it could produce a bosenova, leaving a dense axion star as the remnant.

  7. Dense Axion Stars

    Science.gov (United States)

    Mohapatra, Abhishek; Braaten, Eric; Zhang, Hong

    2016-03-01

    If the dark matter consists of axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound Bose-Einstein condensates of axions. In the previously known axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure. If the axion mass energy is mc2 =10-4 eV, these dilute axion stars have a maximum mass of about 10-14M⊙ . We point out that there are also dense axion stars in which gravity is balanced by the mean-field pressure of the axion condensate. We study axion stars using the leading term in a systematically improvable approximation to the effective potential of the nonrelativistic effective field theory for axions. Using the Thomas-Fermi approximation in which the kinetic pressure is neglected, we find a sequence of new branches of axion stars in which gravity is balanced by the mean-field interaction energy of the axion condensate. If mc2 =10-4 4 eV, the first branch of these dense axion stars has mass ranging from about 10-11M⊙ toabout M⊙.

  8. Cooling of Neutron Stars

    Directory of Open Access Journals (Sweden)

    Grigorian H.

    2010-10-01

    Full Text Available We introduce the theoretical basis for modeling the cooling evolution of compact stars starting from Boltzmann equations in curved space-time. We open a discussion on observational verification of different neutron star models by consistent statistics. Particular interest has the question of existence of quark matter deep inside of compact object, which has to have a specific influence on the cooling history of the star. Besides of consideration of several constraints and features of cooling evolution, which are susceptible of being critical for internal structure of hot compact stars we have introduced a method of extraction of the mass distribution of the neutron stars from temperature and age data. The resulting mass distribution has been compared with the one suggested by supernove simulations. This method can be considered as an additional checking tool for the consistency of theoretical modeling of neutron stars. We conclude that the cooling data allowed existence of neutron stars with quark cores even with one-flavor quark matter.

  9. A homosexual japanese man with acute hepatitis due to hepatitis B virus genotype ae, concurrent with amebic colitis

    OpenAIRE

    Sakaguchi, Kohsaku; KOBASHI, HARUHIKO; Takaki,Akinobu; Kato, Jun; Nawa,Toru; Tatsukawa, Masashi; ISHIKAWA, SHIN; Iwasaki, Yoshiaki; Miyake,Yasuhiro; Shiratori, Yasushi

    2007-01-01

    We report herein a case with acute hepatitis due to hepatitis B virus genotype Ae, concurrent with amebic colitis. A 39-year-old homosexual Japanese man was admitted to our hospital with jaundice. Laboratory tests showed an elevation of transaminase and positivity for hepatitis B surface antigen and IgM-type antibody to hepatitis B core antigen. The hepatitis B virus genotype was determined to be Ae. Furthermore, a mud-like stool with blood and mucous had sometimes been noted during the past ...

  10. Dynamic destabilization analysis based on AE experiment of deep-seated, steep-inclined and extra-thick coal seam

    Institute of Scientific and Technical Information of China (English)

    Fenhua Ren; Xingping Lai; Meifeng Cai

    2008-01-01

    No. 5 coal seam in Huating Coal Mine is a deep-seated, steep-inclined extra-thick coal seam where excavation disturbance is quite frequent. The maximum and minimum principal stresses differ widely. During mining, dynamical destabilization happens frequently and induce tragedies. Based on the comparison between the acoustic emission (AE) experiment on dynamical destabilization of coal rock and the related in situ testing results, this article provides comprehensive analysis on the regular quantificational AE patterns (energy rate, total events) of coal rock destabilization in complex-variable environment. The comparison parameters include dynamic tension energy rate, deformation resistance to compression, and shear stress.

  11. A Novel Approach for Star Extraction from Star Image

    Institute of Scientific and Technical Information of China (English)

    ZHENGSheng; LIUJian; TIANJinwen; YANGRuijuan

    2005-01-01

    Star acquisition is one of the most timeconsuming routines in star tracker operation. One star Point spread function (PSF) forms a near Gaussian distribution in the star image, the star image can be regarded as 2-D intensity surface, and every pixel is the sampled point. The star cluster grouping is to find the highes tintensity pixel among the PSFs and collect the adjacent pixels and group them. The possible highest intensity pixels are the maximum extremum points of the 2-D intensity surface. To efficiently extract star from the star image, a novel star acquisition approach, which uses the simplified least squares support vector machines regression algorithm to find the optimal intensity surface function and predictthe maximum extremum points, is proposed. Comput erexperiments are carried out for the simulated star images.The experimental results demonstrate that the proposed method has a lot of advantages, including the high efficiency and good robustness over a wide range of sensor noise.

  12. Infrared spectroscopy of stars

    Science.gov (United States)

    Merrill, K. M.; Ridgway, S. T.

    1979-01-01

    This paper reviews applications of IR techniques in stellar classification, studies of stellar photospheres, elemental and isotopic abundances, and the nature of remnant and ejected matter in near-circumstellar regions. Qualitative IR spectral classification of cool and hot stars is discussed, along with IR spectra of peculiar composite star systems and of obscured stars, and IR characteristics of stellar populations. The use of IR spectroscopy in theoretical modeling of stellar atmospheres is examined, IR indicators of stellar atmospheric composition are described, and contributions of IR spectroscopy to the study of stellar recycling of interstellar matter are summarized. The future of IR astronomy is also considered.

  13. Nuclear physics of stars

    CERN Document Server

    Iliadis, Christian

    2007-01-01

    Thermonuclear reactions in stars is a major topic in the field of nuclear astrophysics, and deals with the topics of how precisely stars generate their energy through nuclear reactions, and how these nuclear reactions create the elements the stars, planets and - ultimately - we humans consist of. The present book treats these topics in detail. It also presents the nuclear reaction and structure theory, thermonuclear reaction rate formalism and stellar nucleosynthesis. The topics are discussed in a coherent way, enabling the reader to grasp their interconnections intuitively. The book serves bo

  14. Entropy Production of Stars

    Directory of Open Access Journals (Sweden)

    Leonid M. Martyushev

    2015-06-01

    Full Text Available The entropy production (inside the volume bounded by a photosphere of main-sequence stars, subgiants, giants, and supergiants is calculated based on B–V photometry data. A non-linear inverse relationship of thermodynamic fluxes and forces as well as an almost constant specific (per volume entropy production of main-sequence stars (for 95% of stars, this quantity lies within 0.5 to 2.2 of the corresponding solar magnitude is found. The obtained results are discussed from the perspective of known extreme principles related to entropy production.

  15. Insecticidal activity of Vip3Aa, Vip3Ad, Vip3Ae, and Vip3Af from Bacillus thuringiensis against lepidopteran corn pests.

    Science.gov (United States)

    Hernández-Martínez, Patricia; Hernández-Rodríguez, Carmen Sara; Rie, Jeroen Van; Escriche, Baltasar; Ferré, Juan

    2013-05-01

    Vip3Aa, Vip3Ad, Vip3Ae, and Vip3Af proteins from Bacillus thuringiensis were tested for their toxicity against Spodoptera frugiperda and Agrotis ipsilon. Vip3Ad was non-toxic to the two species. Vip3Ae and Vip3Af were significantly more toxic than Vip3Aa against S. frugiperda, both as protoxins and as toxins. Against A. ipsilon, Vip3Ae protoxin was more toxic than Vip3Aa and Vip3Af protoxins. Purification by metal-chelate affinity chromatography significantly affected Vip3Ae toxicity against the two insect species.

  16. Stress estimation around the survey wells in Hanshin-Awaji area by means of AE/DR and DSCA experiments; AE/DR ho to DSCA ho ni yoru Hanshin Awaji chiiki chosa kui shuhen no chikaku oryoku sokutei

    Energy Technology Data Exchange (ETDEWEB)

    Ito, H.; Kuwahara, Y.; Nishizawa, O. [Geological Survey of Japan, Tsukuba (Japan); Yamamoto, K. [Tohoku University, Sendai (Japan). Faculty of Science; Sano, O. [Yamaguchi University, Yamaguchi (Japan). Faculty of Engineering; Yokoyama, T.; Kudo, R. [OYO Corp., Tokyo (Japan); Xue, Z. [Kiso-Jiban Consultants Co. Ltd., Tokyo (Japan)

    1996-05-01

    A total of 5 wells were excavated in the Hanshin-Awaji area (Ikeda, Takarazuka, Tarumi, Hirabayashi and Ikunami) to collect the core samples, which were analyzed by the AE/DR and DSCA methods to determine crustal stresses. For the AE/DR analysis, the core sample was cut in the vertical direction, and in the horizontal direction at intervals of 45{degree}. The sample of unknown orientation was provided with a datum line common for both methods, to compare the results by these methods. A load was applied to the sample, provided with an AE sensor and strain gauge on the sides, in the longitudinal direction. For the DSCA analysis, the core sample was cut into a cube having a side length of 33mm, with a pair of planes directed in parallel to the datum line. A total of 18 strain gauges, 10mm in gauge length, were attached to the cube. The AE/DR analysis gave the maximum and minimum principal stresses in the horizontal plane and stresses in the vertical direction, whereas the DSCA the maximum, intermediate and minimum principal stresses. 3 refs., 7 figs.

  17. Temperature of neutron stars

    Science.gov (United States)

    Tsuruta, Sachiko

    2016-07-01

    We start with a brief introduction to the historical background in the early pioneering days when the first neutron star thermal evolution calculations predicted the presence of neutron stars hot enough to be observable. We then report on the first detection of neutron star temperatures by ROSAT X-ray satellite, which vindicated the earlier prediction of hot neutron stars. We proceed to present subsequent developments, both in theory and observation, up to today. We then discuss the current status and the future prospect, which will offer useful insight to the understanding of basic properties of ultra-high density matter beyond the nuclear density, such as the possible presence of such exotic particles as pion condensates.

  18. Stars resembling the Sun

    Science.gov (United States)

    Cayrel de Strobel, G.

    This review is primarily directed to the question whether photometric solar analogues remain such when subjected to detailed spectroscopic analyses and interpreted with the help of internal stucture models. In other words, whether the physical parameters: mass, chemical composition, age (determining effective temperature and luminosity), chromospheric activity, equatorial rotation, lithium abundance, velocity fields etc., we derive from the spectral analysis of a photometric solar analogue, are really close to those of the Sun. We start from 109 photometric solar analogues extracted from different authors. The stars selected had to satisfy three conditions: i) their colour index (B-V) must be contained in the interval: Δ (B-V) = 0.59-0.69, ii) they must possess a trigonometric parallax, iii) they must have undergone a high resolution detailed spectroscopic analysis. First, this review presents photometric and spectrophotometric researches on solar analogues and recalls the pionneering work on these stars by the late Johannes Hardorp. After a brief discussion on low and high resolution spectroscopic researches, a comparison is made between effective temperatures as obtained, directly, from detailed spectral analyses and those obtained, indirectly, from different photometric relations. An interesting point in this review is the discussion on the tantalilizing value of the (B-V)solar of the Sun, and the presentation of a new reliable value of this index. A short restatement of the kinematic properties of the sample of solar analogues is also made. And, finally, the observational ( T eff, M bol) diagram, obtained with 99 of the initially presented 109 analogues, is compared to a theoretical ( T eff, M bol) diagram. This latter has been constructed with a grid of internal structure models for which, (very important for this investigation), the Sun was used as gauge. In analysing the position, with respect to the Sun, of each star we hoped to find a certain number of

  19. Notes on Star Formation

    CERN Document Server

    Krumholz, Mark R

    2015-01-01

    This book provides an introduction to the field of star formation at a level suitable for graduate students or advanced undergraduates in astronomy or physics. The structure of the book is as follows. The first two chapters begin with a discussion of observational techniques, and the basic phenomenology they reveal. The goal is to familiarize students with the basic techniques that will be used throughout, and to provide a common vocabulary for the rest of the book. The next five chapters provide a similar review of the basic physical processes that are important for star formation. Again, the goal is to provide a basis for what follows. The remaining chapters discuss star formation over a variety of scales, starting with the galactic scale and working down to the scales of individual stars and their disks. The book concludes with a brief discussion of the clearing of disks and the transition to planet formation. The book includes five problem sets, complete with solutions.

  20. Spectroscopy among the stars.

    Science.gov (United States)

    Winnewisser, G

    1996-06-01

    The space between the stars is not void, but filled with interstellar matter, mainly composed of dust and gas, which gather in large interstellar clouds. In our Galaxy these interstellar clouds are distributed along a thin, but extended layer which basically traces out the spiral distribution of matter: the stars, the gas, and the dust component. Up to the present time more than 100 different molecules have been identified in interstellar molecular clouds. The majority of the interstellar molecules constitute carbon containing organic substances. During the past years, overwhelming evidence has been gathered, mainly through spectroscopic observations, that interstellar molecular clouds provide the birthplaces for stars. In fact detailed high spectral and spatial resolution spectroscopic measurements reveal physical and chemical processes of the intricate star formation process.

  1. Interferometric star tracker Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Optical Physics Company (OPC) proposes to develop a high accuracy version of its interferometric star tracker capable of meeting the milli-arcsecond-level pointing...

  2. Sports Stars Shine

    Institute of Scientific and Technical Information of China (English)

    Yu Yan

    2012-01-01

    Alive and exciting award ceremony drew the attention of numerous Chinese households on the night of January 15.The most popular Chinese sports stars attended the 2011 CCTV Sports Personality Award Ceremony at the National Indoor Stadium in Beijing.

  3. Neutron Stars Recent Developments

    CERN Document Server

    Heiselberg, H

    1999-01-01

    Recent developments in neutron star theory and observation are discussed. Based on modern nucleon-nucleon potentials more reliable equations of state for dense nuclear matter have been constructed. Furthermore, phase transitions such as pion, kaon and hyperon condensation, superfluidity and quark matter can occur in cores of neutron stars. Specifically, the nuclear to quark matter phase transition and its mixed phases with intriguing structures is treated. Rotating neutron stars with and without phase transitions are discussed and compared to observed masses, radii and glitches. The observations of possible heavy $\\sim 2M_\\odot$ neutron stars in X-ray binaries and QPO's require relatively stiff equation of states and restrict strong phase transitions to occur at very high nuclear densities only.

  4. Worlds around other stars

    Science.gov (United States)

    Black, David C.

    1991-01-01

    The possible, though tentative, detection of planetary companions to other stars which may be capable of supporting life as we know it through the use of a new generation of detectors and telescopes, combined with some innovative detection techniques, is discussed. The current view of the origin of the solar system, based on the nebular hypothesis, is discussed as it pertains to the formation of how and where planets form and, hence, how and where to search for them. Both direct methods of search for other planetary systems, which involve detecting reflected light or infrared radiation form the planets themselves, and indirect methods, which involve the scrutinization of a star for signs that it is responding to the gravitational tug of an orbiting planet, are discussed at length. In particular, various methods for detecting minute velocity perturbations of stars are discussed. It is noted that the study of brown dwarfs may also provide clues on the formation of stars and planets.

  5. Chaotic Star Birth

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Click on the image for Poster VersionClick on the image for IRAS 4B Inset Located 1,000 light years from Earth in the constellation Perseus, a reflection nebula called NGC 1333 epitomizes the beautiful chaos of a dense group of stars being born. Most of the visible light from the young stars in this region is obscured by the dense, dusty cloud in which they formed. With NASA's Spitzer Space Telescope, scientists can detect the infrared light from these objects. This allows a look through the dust to gain a more detailed understanding of how stars like our sun begin their lives. The young stars in NGC 1333 do not form a single cluster, but are split between two sub-groups. One group is to the north near the nebula shown as red in the image. The other group is south, where the features shown in yellow and green abound in the densest part of the natal gas cloud. With the sharp infrared eyes of Spitzer, scientists can detect and characterize the warm and dusty disks of material that surround forming stars. By looking for differences in the disk properties between the two subgroups, they hope to find hints of the star and planet formation history of this region. The knotty yellow-green features located in the lower portion of the image are glowing shock fronts where jets of material, spewed from extremely young embryonic stars, are plowing into the cold, dense gas nearby. The sheer number of separate jets that appear in this region is unprecedented. This leads scientists to believe that by stirring up the cold gas, the jets may contribute to the eventual dispersal of the gas cloud, preventing more stars from forming in NGC 1333. In contrast, the upper portion of the image is dominated by the infrared light from warm dust, shown as red.

  6. Alkaline broadening in Stars

    CERN Document Server

    De Kertanguy, A

    2015-01-01

    Giving new insight for line broadening theory for atoms with more structure than hydrogen in most stars. Using symbolic software to build precise wave functions corrected for ds;dp quantum defects. The profiles obtained with that approach, have peculiar trends, narrower than hydrogen, all quantum defects used are taken from atomic database topbase. Illustration of stronger effects of ions and electrons on the alkaline profiles, than neutral-neutral collision mechanism. Keywords : Stars: fundamental parameters - Atomic processes - Line: profiles.

  7. Tomographic Sounding of Protoplanetary and Transitional Disks: Using Inner Disk Variability at Near to Mid-IR Wavelengths to Probe Conditions in the Outer Disk

    Science.gov (United States)

    Grady, C. A.; Sitko, M.L.

    2013-01-01

    Spitzer synoptic monitoring of young stellar associations has demonstrated that variability among young stars and their disks is ubiquitous. The Spitzer studies have been limited by target visibility windows and cover only a short temporal baseline in years. A complementary approach is to focus on stars chosen for high-value observations (e.g. high-contrast imaging, interferometry, or access to wavelengths which are difficult to achieve from the ground) where the synoptic data can augment the imagery or interferometry as well as probing disk structure. In this talk, we discuss how synoptic data for two protoplanetary disks, MWC 480 and HD 163296, constrain the dust disk scale height, account for variable disk illumination, and can be used to locate emission features, such as the IR bands commonly associated with PAHs in the disk, as part of our SOFIA cycle 1 study. Similar variability is now known for several pre-transitional disks, where synoptic data can be used to identify inner disks which are not coplanar with the outer disk, and which may be relicts of giant planet-giant planet scattering events. Despite the logistical difficulties in arranging supporting, coordinated observations in tandem with high-value observations, such data have allowed us to place imagery in context, constrained structures in inner disks not accessible to direct imagery, and may be a tool for identifying systems where planet scattering events have occurred.

  8. Distant star clusters of the Milky Way in MOND

    CERN Document Server

    Haghi, Hossein; Kroupa, Pavel

    2011-01-01

    We determine the mean velocity dispersion of six Galactic outer halo globular clusters, AM 1, Eridanus, Pal 3, Pal 4, Pal 15, and Arp 2 in the weak acceleration regime to test classical vs. modified Newtonian dynamics (MOND). Owing to the non-linearity of MOND's Poisson equation, beyond tidal effects, the internal dynamics of clusters is affected by the external field in which they are immersed. For the studied clusters, particle accelerations are much lower than the critical acceleration a_0 of MOND, but the motion of stars is neither dominated by internal accelerations (a_i >> a_e) nor external accelerations (a_e >> a_i). We use the N-body code N-MODY in our analysis, which is a particle-mesh-based code with a numerical MOND potential solver developed by Ciotti, Londrillo, and Nipoti (2006) to derive the line-of-sight velocity dispersion by adding the external field effect. We show that Newtonian dynamics predicts a low-velocity dispersion for each cluster, while in modified Newtonian dynamics the velocity ...

  9. Characterization of titanium hydride film after long-term air interaction: SEM, ARXPS and AES depth profile studies

    NARCIS (Netherlands)

    Lisowski, W.; Berg, van den A.H.J.; Smithers, M.

    1998-01-01

    Thin titanium hydride (TiHy) films are compared with thin titanium films after analysis using a combination of scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and angle-resolved x-ray photoelectron spectroscopy (ARXPS). The TiHy films were prepared under ultrahigh vacuum condit

  10. Dosimetry of 64Cu-DOTA-AE105, a PET tracer for uPAR imaging

    DEFF Research Database (Denmark)

    Persson, Morten; El Ali, Henrik H.; Binderup, Tina

    2014-01-01

    of another 64Cu-DOTA peptide-based tracer, 64Cu-DOTA-TATE, and underwent same procedure as just described. The human dosimetry estimates were then compared with observed human dosimetry estimate recently found in a first-in-man study using 64Cu-DOTA-TATE. ResultsHuman estimates of 64Cu-DOTA-AE105 revealed...

  11. Growth of Ag thin films on ZnO(0 0 0 -1) investigated by AES and STM

    Energy Technology Data Exchange (ETDEWEB)

    Duriau, E. [Interuniversity Microelectronic Center (IMEC), SPDT-MCA, Kapeldreef 75, B-3001 Leuven (Belgium); Agouram, S. [Dpto. Fisica Aplicada y Electromagnetismo c/Dr. Moliner no. 50, 46100 Burjassot, Valencia (Spain); Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Morhain, C. [Centre de Recherche sur l' HeteroEpitaxie et ses Applications (CRHEA), CNRS, Rue Bernard Gregory, F-06560 Valbonne Sophia-Antipolis (France); Seldrum, T. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Sporken, R. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Dumont, J. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium)]. E-mail: jacques.dumont@fundp.ac.be

    2006-11-15

    The growth of Ag films on ZnO(0 0 0 -1) has been investigated by Auger electron spectroscopy (AES) and scanning tunneling microscopy (STM). A high density of islands is nucleated at the earliest stages of the growth. An upstepping mechanism causes these islands to coalesce while the uncovered fraction of the ZnO surface remains constant (30%)

  12. 42 CFR 84.160 - Man test for gases and vapors; Type A and Type AE respirators; test requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Man test for gases and vapors; Type A and Type AE respirators; test requirements. 84.160 Section 84.160 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES...

  13. 75 FR 353 - AES Sparrows Point LNG, LLC and Mid-Atlantic Express, LLC; Notice of Availability of the Final...

    Science.gov (United States)

    2010-01-05

    ...; CP07-63-000] AES Sparrows Point LNG, LLC and Mid-Atlantic Express, LLC; Notice of Availability of the Final General Conformity Determination for Maryland for the Proposed Sparrows Point LNG Terminal and... potential air quality impacts associated with the construction and operation of a liquefied natural gas...

  14. 42 CFR 84.153 - Airflow resistance test, Type A and Type AE supplied-air respirators; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... supplied-air respirators; minimum requirements. 84.153 Section 84.153 Public Health PUBLIC HEALTH SERVICE... APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Supplied-Air Respirators § 84.153 Airflow resistance test, Type A and Type AE supplied-air respirators; minimum requirements. (a) Airflow resistance will...

  15. Chloride Accumulators NKCC1 and AE2 in Mouse GnRH Neurons: Implications for GABAA Mediated Excitation.

    Directory of Open Access Journals (Sweden)

    Carol Taylor-Burds

    Full Text Available A developmental "switch" in chloride transporters occurs in most neurons resulting in GABAA mediated hyperpolarization in the adult. However, several neuronal cell subtypes maintain primarily depolarizing responses to GABAA receptor activation. Among this group are gonadotropin-releasing hormone-1 (GnRH neurons, which control puberty and reproduction. NKCC1 is the primary chloride accumulator in neurons, expressed at high levels early in development and contributes to depolarization after GABAA receptor activation. In contrast, KCC2 is the primary chloride extruder in neurons, expressed at high levels in the adult and contributes to hyperpolarization after GABAA receptor activation. Anion exchangers (AEs are also potential modulators of responses to GABAA activation since they accumulate chloride and extrude bicarbonate. To evaluate the mechanism(s underlying GABAA mediated depolarization, GnRH neurons were analyzed for 1 expression of chloride transporters and AEs in embryonic, pre-pubertal, and adult mice 2 responses to GABAA receptor activation in NKCC1-/- mice and 3 function of AEs in these responses. At all ages, GnRH neurons were immunopositive for NKCC1 and AE2 but not KCC2 or AE3. Using explants, calcium imaging and gramicidin perforated patch clamp techniques we found that GnRH neurons from NKCC1-/- mice retained relatively normal responses to the GABAA agonist muscimol. However, acute pharmacological inhibition of NKCC1 with bumetanide eliminated the depolarization/calcium response to muscimol in 40% of GnRH neurons from WT mice. In the remaining GnRH neurons, HCO3- mediated mechanisms accounted for the remaining calcium responses to muscimol. Collectively these data reveal mechanisms responsible for maintaining depolarizing GABAA mediated transmission in GnRH neurons.

  16. Life Cycle of Stars

    Science.gov (United States)

    1999-01-01

    In this stunning picture of the giant galactic nebula NGC 3603, the crisp resolution of NASA's Hubble Space Telescope captures various stages of the life cycle of stars in one single view. To the upper left of center is the evolved blue supergiant called Sher 25. The star has a unique circumstellar ring of glowing gas that is a galactic twin to the famous ring around the supernova 1987A. The grayish-bluish color of the ring and the bipolar outflows (blobs to the upper right and lower left of the star) indicates the presence of processed (chemically enriched) material. Near the center of the view is a so-called starburst cluster dominated by young, hot Wolf-Rayet stars and early O-type stars. A torrent of ionizing radiation and fast stellar winds from these massive stars has blown a large cavity around the cluster. The most spectacular evidence for the interaction of ionizing radiation with cold molecular-hydrogen cloud material are the giant gaseous pillars to the right of the cluster. These pillars are sculptured by the same physical processes as the famous pillars Hubble photographed in the M16 Eagle Nebula. Dark clouds at the upper right are so-called Bok globules, which are probably in an earlier stage of star formation. To the lower left of the cluster are two compact, tadpole-shaped emission nebulae. Similar structures were found by Hubble in Orion, and have been interpreted as gas and dust evaporation from possibly protoplanetary disks (proplyds). This true-color picture was taken on March 5, 1999 with the Wide Field Planetary Camera 2.

  17. NuSTAR Results and Future Plans for Magnetar and Rotation-Powered Pulsar Observations

    Science.gov (United States)

    An, H.; Kaspi, V. M.; Archibald, R.; Bachetti, M.; Bhalerao, V.; Bellm, E. C.; Beloborodov, A. M.; Boggs, S. E.; Chakrabarty, D.; Christensen, F. E.; Craig, W. W.; Dufour, F.; Forster, K.; Gotthelf, B. W.; Grefenstette, B. W.; Hailey, C. J.; Harrison, F. A.; Hascoet, R.; Kitaguchi, T.; Kouveliotou, Ch.; Madsen, K. K.; Mori, K.; Pivovaroff, M. J.; Rana, V. R.; Stern, D.; Tendulkar, S.; Tomsick, J. A.; Vogel, J. K.; Zhang, William W.

    2014-01-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR) is the first focusing hard X-ray mission in orbit and operates in the 3-79 keV range. NuSTAR's sensitivity is roughly two orders of magnitude better than previous missions in this energy band thanks to its superb angular resolution. Since its launch in 2012 June, NuSTAR has performed excellently and observed many interesting sources including four magnetars, two rotation-powered pulsars and the cataclysmic variable AE Aquarii. NuSTAR also discovered 3.76-s pulsations from the transient source SGR J1745-29 recently found by Swift very close to the Galactic center, clearly identifying the source as a transient magnetar. For magnetar 1E 1841-045, we show that the spectrum is well fit by an absorbed blackbody plus broken power-law model with a hard power-law photon index of approximately 1.3. This is consistent with previous results by INTEGRAL and RXTE. We also find an interesting double-peaked pulse profile in the 25-35 keV band. For AE Aquarii, we show that the spectrum can be described by a multi-temperature thermal model or a thermal plus non-thermal model; a multi-temperature thermal model without a non-thermal component cannot be ruled out. Furthermore, we do not see a spiky pulse profile in the hard X-ray band, as previously reported based on Suzaku observations. For other magnetars and rotation-powered pulsars observed with NuSTAR, data analysis results will be soon available.

  18. Temporal patterns of abundance of Aedes aegypti and Aedes albopictus (Diptera: Culicidae and mitochondrial DNA analysis of Ae. albopictus in the Central African Republic.

    Directory of Open Access Journals (Sweden)

    Basile Kamgang

    Full Text Available The invasive Asian tiger mosquito Aedes albopictus (Diptera: Culicidae was first reported in central Africa in 2000, in Cameroon, with the indigenous mosquito species Ae. aegypti (Diptera: Culicidae. Today, this invasive species is present in almost all countries of the region, including the Central African Republic (CAR, where it was first recorded in 2009. As invasive species of mosquitoes can affect the distribution of native species, resulting in new patterns of vectors and concomitant risk for disease, we undertook a comparative study early and late in the wet season in the capital and the main cities of CAR to document infestation and the ecological preferences of the two species. In addition, we determined the probable geographical origin of invasive populations of Ae. albopictus with two mitochondrial DNA genes, COI and ND5. Analysis revealed that Ae. aegypti was more abundant earlier in the wet season and Ae. albopictus in the late wet season. Used tyres were the most heavily colonized productive larval habitats for both species in both seasons. The invasive species Ae. albopictus predominated over the resident species at all sites in which the two species were sympatric. Mitochondrial DNA analysis revealed broad low genetic diversity, confirming recent introduction of Ae. albopictus in CAR. Phylogeographical analysis based on COI polymorphism indicated that the Ae. albopictus haplotype in the CAR population segregated into two lineages, suggesting multiple sources of Ae. albopictus. These data may have important implications for vector control strategies in central Africa.

  19. Dark Stars: A Review

    CERN Document Server

    Freese, Katherine; Spolyar, Douglas; Valluri, Monica

    2015-01-01

    Dark Stars (DS) are stellar objects made (almost entirely) of ordinary atomic material but powered by the heat from Dark Matter (DM) annihilation (rather than by fusion). Weakly Interacting Massive Particles (WIMPs), among the best candidates for DM, can be their own antimatter and can accumulate inside the star, with their annihilation products thermalizing with and heating the DS. The resulting DSs are in hydrostatic and thermal equilibrium. The first phase of stellar evolution in the history of the Universe may have been dark stars. Though DM constituted only $10^6 M_\\odot$), very bright ($>10^9 L_\\odot$), and potentially detectable with the James Webb Space Telescope (JWST). Once the DM runs out and the dark star dies, it may collapse to a black hole; thus DSs can provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The curre...

  20. Stars, Galaxies and Quasars

    Directory of Open Access Journals (Sweden)

    Patrick Das Gupta

    2009-05-01

    Full Text Available This article provides a brief introduction to the basics of stars, galaxies and Quasi-stellar objects (QSOs. In stars, the central pressure and temperature must be high in order to halt the stellar gravitational collapse. High temperature leads to thermonuclear fusion in the stellar core, releasing thereby enormous amount of nuclear energy, making the star shine brilliantly. On the other hand, the QSOs are very bright nuclei lying in the centres of some galaxies. Many of these active galactic nuclei, which appear star-like when observed through a telescope and  whose power output are more than 1011 times that of the Sun, exhibit rapid time variability in their X-ray emissions.  Rapid variability along with the existence of a maximum speed limit, c, provide a strong argument in favour of a compact central engine model for QSOs in which a thick disc of hot gas going around a supermassive blackhole is what makes a QSO appear like a bright point source. Hence, unlike stars, QSOs are powered by gravitational potential energy.

  1. Hot subluminous stars

    CERN Document Server

    Heber, Ulrich

    2016-01-01

    Hot subluminous stars of spectral type B and O are core helium-burning stars at the blue end of the horizontal branch or have evolved even beyond that stage. Strikingly, the distribution in the Hertzsprung-Russell diagram of He-rich vs. He-poor hot subdwarf stars of the globular clusters omega Cen and NGC~2808 differ from that of their field counterparts. The metal-abundance patterns of hot subdwarfs are typically characterized by strong deficiencies of some lighter elements as well as large enrichments of heavy elements. A large fraction of sdB stars are found in close binaries with white dwarf or very low-mass main sequence companions, which must have gone through a common-envelope phase of evolution.They provide a clean-cut laboratory to study this important but yet purely understood phase of stellar evolution. Substellar companions to sdB stars have also been found. For HW~Vir systems the companion mass distribution extends from the stellar into the brown dwarf regime. A giant planet to the pulsator V391 ...

  2. Circulation of Stars

    Science.gov (United States)

    Boitani, P.

    2016-01-01

    Since the dawn of man, contemplation of the stars has been a primary impulse in human beings, who proliferated their knowledge of the stars all over the world. Aristotle sees this as the product of primeval and perennial “wonder” which gives rise to what we call science, philosophy, and poetry. Astronomy, astrology, and star art (painting, architecture, literature, and music) go hand in hand through millennia in all cultures of the planet (and all use catasterisms to explain certain phenomena). Some of these developments are independent of each other, i.e., they take place in one culture independently of others. Some, on the other hand, are the product of the “circulation of stars.” There are two ways of looking at this. One seeks out forms, the other concentrates on the passing of specific lore from one area to another through time. The former relies on archetypes (for instance, with catasterism), the latter constitutes a historical process. In this paper I present some of the surprising ways in which the circulation of stars has occurred—from East to West, from East to the Far East, and from West to East, at times simultaneously.

  3. Young Stars with SALT

    CERN Document Server

    Riedel, Adric R; Rice, Emily L; Cruz, Kelle L; Henry, Todd J

    2016-01-01

    We present a spectroscopic and kinematic analysis of 79 nearby M dwarfs in 77 systems. All are low-proper-motion southern hemisphere objects and were identified in a nearby star survey with a demonstrated sensitivity to young stars. Using low-resolution optical spectroscopy from the Red Side Spectrograph (RSS) on the South African Large Telescope (SALT), we have determined radial velocities, H-alpha, Lithium 6708\\AA, and Potassium 7699\\AA~equivalent widths linked to age and activity, and spectral types for all our targets. Combined with astrometric information from literature sources, we identify 44 young stars. Eighteen are previously known members of moving groups within 100 parsecs of the Sun. Twelve are new members, including one member of the TW Hydra moving group, one member of the 32 Orionis moving group, nine members of Tucana-Horologium, one member of Argus, and two new members of AB Doradus. We also find fourteen young star systems that are not members of any known groups. The remaining 33 star syst...

  4. Features of the Matter Flows in the Peculiar Cataclysmic Variable AE Aquarii

    CERN Document Server

    Isakova, P B; Zhilkin, A G; Bisikalo, D V; Beskrovnaya, N G

    2016-01-01

    The structure of plasma flows in close binary systems in which one of the components is a rapidly rotating magnetic white dwarf is studied. The main example considered is the AE Aquarii system; the spin period of the white dwarf is about a factor of 1000 shorter than the orbital period, and the magnetic field on the white dwarf surface is of order of 50 MG. The mass transfer in this system was analyzed via numerical solution of the system of MHD equations. These computations show that the magnetic field of the white dwarf does not significantly influence the velocity field of the material in its Roche lobe in the case of laminar flow regime, so that the field does not hinder the formation of a transient disk (ring) surrounding the magnetosphere. However, the efficiency of the energy and angular momentum exchange between the white dwarf and the surrounding material increases considerably with the development of turbulent motions in the matter, resulting in its acceleration at the magnetospheric boundary and fu...

  5. A Novel Steganographic Scheme Based on Hash Function Coupled With AES Encryption

    Directory of Open Access Journals (Sweden)

    Rinu Tresa M J

    2014-04-01

    Full Text Available In the present scenario the use of images increased extremely in the cyber world so that we can easily transfer data with the help of these images in a secured way. Image steganography becomes important in this manner. Steganography and cryptography are the two techniques that are often confused with each other. The input and output of steganogra phy looks alike, but for cryptography the output will be in an encrypted form which always draws attraction to the attacker. This paper combines both steganography and cryptography so that attacker doesn’t know about the existence of message and the message itself is encrypted to ensure more security. The textual data entered by the user is encrypted using AES algorithm. After encryption, the encrypted data is stored in the colour image by using a hash based algorithm. Most of the steganographic algorithms available today is suitable for a specific image format and these algorithms suffers from poor quality of the embedded image. The proposed work does not corrupt the images quality in any form. The striking feature is that this algorithm is suitable for almost all image formats e.g.: jpeg/jpg, Bitmap, TIFF and GIF

  6. Self-Partial and Dynamic Reconfiguration Implementation for AES using FPGA

    Directory of Open Access Journals (Sweden)

    Zine El Abidine Alaoui Ismaili

    2009-08-01

    Full Text Available This paper addresses efficient hardware/software implementation approaches for the AES (Advanced Encryption Standard algorithm and describes the design and performance testing algorithm for embedded system. Also, with the spread of reconfigurable hardware such as FPGAs (Field Programmable Gate Array embedded cryptographic hardware became cost-effective. Nevertheless, it is worthy to note that nowadays, even hardwired cryptographic algorithms are not so safe. From another side, the self-reconfiguring platform is reported that enables an FPGA to dynamically reconfigure itself under the control of an embedded microprocessor. Hardware acceleration significantly increases the performance of embedded systems built on programmable logic. Allowing a FPGA-based MicroBlaze processor to self-select the coprocessors uses can help reduce area requirements and increase a system's versatility. The architecture proposed in this paper is an optimal hardware implementation algorithm and takes dynamic partially reconfigurable of FPGA. This implementation is good solution to preserve confidentiality and accessibility to the information in the numeric communication.

  7. Microwave assisted extraction for trace element analysis of plant materials by ICP-AES

    Energy Technology Data Exchange (ETDEWEB)

    Borkowska-Burnecka, J. [Wroclaw Univ. (Poland). Inst. Chemii

    2000-11-01

    Application of microwave assisted extraction for the decomposition and dissolution of plant samples for trace metal determination by ICP-AES was examined. Dried onion, leaves of spinach beet and three reference materials CTA-OTL-1, CTA-VTL-2 and CL-1 were analyzed. Water, EDTA and hydrochloric acid (0.01, 0.10 and 1.0 M, respectively) were used as leaching solutions. The extraction efficiency was investigated by comparison of the results with those obtained after microwave wet digestion. HCl was found to be very suitable for quantitative extraction of B, Ba, Cd, Cu, Mn, Ni, Pb, Sr and Zn from the samples. For reference materials, the measured concentrations are well consistent with the certified values. The use of EDTA led to a complete extraction of B, Cd, Ni, Pb, Sr and Zn. Water was found to be a good leaching solution for boron. For extraction with HCl and EDTA, the RSD values for the concentrations measured were below 8% for most of the elements. (orig.)

  8. IMAGE STEGANOGRAPHY BASED ON TRANSFORM DOMAIN, BLOWFISH AND AES FOR SECOND LEVEL SECURITY

    Directory of Open Access Journals (Sweden)

    Janki Gajjar

    2015-10-01

    Full Text Available Steganography is technique for secret communication. It hides the existence of the communication between parties. So viewer cannot detect the existence of the message and also not detect the communication channel. So attacker cannot modify and see the secret information. In image steganography, secrecy is accomplished by hide the secret message in cover image using steganography techniques. There are different types of steganography techniques each have their merits and demerits. Using Steganography techniques on cover image we can improve the security and robustness. For improving second level security we are using cryptography. Cryptography is used to convert the secret message in cipher text means unreadable form of message. Cryptography introduces many algorithms. This algorithm converts the secret message in cipher text. In our proposed method we are using Blowfish and AES algorithm for converting the message in cipher text and then hide this cipher text in cover image using DCT steganography technique. Using this combine technique we can get the stego-image. Here using this proposed method we can get the security and robustness in terms of message when we retrieve the message from the stego-image.

  9. PIXE and ICP-AES analysis of early glass unearthed from Xinjiang (China)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, B. [Department of Technical Physics, School of Physics, Peking University, Beijing 100871 (China); Cheng, H.S. [Institute of Modern Physics, Fudan University, Shanghai 200433 (China)]. E-mail: hscheng@fudan.edu.cn; Ma, B. [School of Information Science and Engineering, Fudan University, Shanghai 200433 (China); Li, Q.H. [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhang, P. [Xinjiang Institute of Archaeology, Urumchi 830011 (China); Gan, F.X. [School of Information Science and Engineering, Fudan University, Shanghai 200433 (China); Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Yang, F.J. [Institute of Modern Physics, Fudan University, Shanghai 200433 (China)

    2005-10-15

    Early glasses (about 1066 BC-220 AD) unearthed from Xinjiang of China were chemically characterized by using PIXE and ICP-AES. It was found that these glasses were basically attributed to PbO-BaO-SiO{sub 2} system, K{sub 2}O-SiO{sub 2} system, Na{sub 2}O-CaO-SiO{sub 2} system and Na{sub 2}O-CaO-PbO-SiO{sub 2} system. The results from the cluster analysis showed that some glasses had basically similar recipe and technology. The PbO-BaO-SiO{sub 2} glass and the K{sub 2}O-SiO{sub 2} glass were thought to come from the central area and the south of ancient China, respectively. The part of the Na{sub 2}O-CaO-SiO{sub 2} glass (including the Na{sub 2}O-CaO-PbO-SiO{sub 2} glass) might be imported from Mesopotamia, while the other part might be locally produced.

  10. Ambiguities in Determination Of Self-Affinity in the AE-index Time Series

    CERN Document Server

    Watkins, N W; Rhodes, C S; Rowlands, G

    2001-01-01

    The interaction between the Earth's magnetic field and the solar wind plasma results in a natural plasma confinement system which stores energy. Dissipation of this energy through Joule heating in the ionosphere can be studied via the Auroral Electrojet (AE) index. The apparent broken power law form of the frequency spectrum of this index has motivated investigation of whether it can be described as fractal coloured noise. One frequently-applied test for self-affinity is to demonstrate linear scaling of the logarithm of the structure function of a time series with the logarithm of the dilation factor $\\lambda$. We point out that, while this is conclusive when applied to signals that are self-affine over many decades in $\\lambda$, such as Brownian motion, the slope deviates from exact linearity and the conclusions become ambiguous when the test is used over shorter ranges of $\\lambda$. We demonstrate that non self-affine time series made up of random pulses can show near-linear scaling over a finite dynamic ra...

  11. Estimation of trace impurities in reactor-grade uranium using ICP-AES.

    Science.gov (United States)

    Malhotra, R K; Satyanarayana, K

    1999-10-01

    Estimation of impurities in reactor grade uranium is important from the point of view of neutron economy. For chemical separation, ion exchange and solvent extraction techniques have been employed although the latter is generally preferred. Amongst various extractants TBP (tri-n-butyl phosphate), TBP-TOPO (tri-n-octyl phosphine oxide), or TOPO only (in CCl(4), xylene, dodecane) is most often used. New reagents like Cyanex-923 (mixture of 4 tri-alkyl phosphine oxides)/TEHP (tri-ethylhexyl phosphoric acid) are also being used. This communication reports chemical separation of uranium by precipitation using 1,2-diaminocyclohexane NNN'N'-tetra acetic acid (CyDTA)/ammonium hydroxide in presence of 1,10-phenanthroline and estimation of impurities in the filtrate by ICP-AES. Quantitative separation of U, a high spectral interferent in plasma and recovery of impurities have been achieved. Recovery of Cd has been improved by using 1,10-phenanthroline. The method is accurate and precise, offering a relative standard deviation ranging from less than 4% (3.8% for Eu at the 10mug g(-1) level) to 12.9% (for Ce at the 2.5 mug g(-1) level) for all the elements studied.

  12. Adenovirus E1A/E1B Transformed Amniotic Fluid Cells Support Human Cytomegalovirus Replication

    Directory of Open Access Journals (Sweden)

    Natascha Krömmelbein

    2016-02-01

    Full Text Available The human cytomegalovirus (HCMV replicates to high titers in primary human fibroblast cell cultures. A variety of primary human cells and some tumor-derived cell lines do also support permissive HCMV replication, yet at low levels. Cell lines established by transfection of the transforming functions of adenoviruses have been notoriously resistant to HCMV replication and progeny production. Here, we provide first-time evidence that a permanent cell line immortalized by adenovirus type 5 E1A and E1B (CAP is supporting the full HCMV replication cycle and is releasing infectious progeny. The CAP cell line had previously been established from amniotic fluid cells which were likely derived from membranes of the developing fetus. These cells can be grown under serum-free conditions. HCMV efficiently penetrated CAP cells, expressed its immediate-early proteins and dispersed restrictive PML-bodies. Viral DNA replication was initiated and viral progeny became detectable by electron microscopy in CAP cells. Furthermore, infectious virus was released from CAP cells, yet to lower levels compared to fibroblasts. Subviral dense bodies were also secreted from CAP cells. The results show that E1A/E1B expression in transformed cells is not generally repressive to HCMV replication and that CAP cells may be a good substrate for dense body based vaccine production.

  13. The Chandra X-Ray Observatory's Radiation Environment and the AP-8/AE-8 Model

    CERN Document Server

    Virani, S N; Plucinsky, P P; Butt, Y M; Virani, Shanil N.; Mueller-Mellin, Reinhold; Plucinsky, Paul P.; Butt, Yousaf M.

    2000-01-01

    The Chandra X-ray Observatory (CXO) was launched on July 23, 1999 and reached its final orbit on August 7, 1999. The CXO is in a highly elliptical orbit, approximately 140,000 km x 10,000 km, and has a period of approximately 63.5 hours (~ 2.65 days). It transits the Earth's Van Allen belts once per orbit during which no science observations can be performed due to the high radiation environment. The Chandra X-ray Observatory Center (CXC) currently uses the National Space Science Data Center's ``near Earth'' AP-8/AE-8 radiation belt model to predict the start and end times of passage through the radiation belts. However, our scheduling software uses only a simple dipole model of the Earth's magnetic field. The resulting B, L magnetic coordinates, do not always give sufficiently accurate predictions of the start and end times of transit of the Van Allen belts. We show this by comparing to the data from Chandra's on-board radiation monitor, the EPHIN (Electron, Proton, Helium Instrument particle detector) instr...

  14. An asynchronous pipeline architecture for the low-power AES S-box

    Institute of Scientific and Technical Information of China (English)

    Zeng Yonghong; Zou Xuecheng; Liu Zhenglin

    2008-01-01

    To obtain a low-power and compact implementation of the advanced encryption standard (AES) S-box, an asynchronous pipeline architecture over composite field arithmetic was proposed in this paper. In the presented S-box, some improvements were made as follows. (1) Level-sensitive latches were inserted in data path to block the propagation of the dynamic hazards, which lowered the power of data path circuit. (2) Operations of latches were controlled by latch controllers based on presented asynchronous sequence element: LC-element, which utilized static asymmetric C-element to construct a simple and power-efficient circuit structure. (3) Implementation of the data path circuit was a semi-custom standard-cell circuit on 0.25μm complementary mental oxide semiconductor (CMOS) process; and the full-custom design methodology was adopted in the handshake circuit design. Experimental results show that the resulting circuit achieves nearly 46% improvement with moderate area penalty (11.7%) compared with the related composite field S-box in power performance. The presented S-box circuit can be a hardware intelligent property (IP) embedded in the targeted systems such as wireless sensor networks (WSN), smartcards and radio frequency identification (RFID).

  15. New Methods of AES Key Expansion%AES密钥扩展新方法

    Institute of Scientific and Technical Information of China (English)

    杨小东; 王毅

    2012-01-01

    在分析原有的AES算法密钥生成改进方法所存在的不足的基础上,根据单向性思想提出了几种新的AES密钥扩展算法,从加密强度和运行速度两方面对原有方法进行了改善.通过分析以及实验数据表明,该方法既保证了密钥扩展算法的安全性,又提高了其运行的效率.%In this paper,based on the analysis of the shortcomings of the original key expansion method,some new methods for the key expansion algorithm of AES encryption algorithm are proposed according to the one-way property,which improved the original method in two aspects-encryption strength and running speed.Analysis and experimental data illustrated that the proposed methods not only guaranteed the security of the original algorithm but also improved its efficiency.

  16. Stars a very short introduction

    CERN Document Server

    King, Andrew

    2012-01-01

    Stars: A Very Short Introduction looks at how stars live, producing all the chemical elements beyond helium, and how they die, leaving remnants such as black holes. Every atom of our bodies has been part of a star. Our very own star, the Sun, is crucial to the development and sustainability of life on Earth. Understanding stars is key to understanding the galaxies they inhabit, the existence of planets, and the history of our entire Universe. This VSI explores the science of stars, the mechanisms that allow them to form, the processes that allow them to shine, and the results of their death.

  17. Cloud Screening and Quality Control Algorithm for Star Photometer Data: Assessment with Lidar Measurements and with All-sky Images

    Science.gov (United States)

    Ramirez, Daniel Perez; Lyamani, H.; Olmo, F. J.; Whiteman, D. N.; Navas-Guzman, F.; Alados-Arboledas, L.

    2012-01-01

    This paper presents the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. These algorithms are necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, delta Ae(lambda), and precipitable water vapor content, W, at nighttime. This cloud screening procedure consists of calculating moving averages of delta Ae() and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable Ae(lambda) and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16 N, 3.60 W, 680 ma.s.l.; South-East of Spain) for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.

  18. Cloud screening and quality control algorithm for star photometer data: assessment with lidar measurements and with all-sky-images

    Directory of Open Access Journals (Sweden)

    D. Pérez-Ramírez

    2012-02-01

    Full Text Available This paper present the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. This kind of algorithms is necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, δAe(λ, and precipitable water vapor content, W, at night-time. This cloud screening procedure consists of calculating moving averages of δAe(λ and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable δAe(λ and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16° N, 3.60° W, 680 m a.s.l.; South-East of Spain for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.

  19. Cloud screening and quality control algorithm for star photometer data: assessment with lidar measurements and with all-sky images

    Directory of Open Access Journals (Sweden)

    D. Pérez-Ramírez

    2012-07-01

    Full Text Available This paper presents the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. These algorithms are necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, δAe(λ, and precipitable water vapor content, W, at nighttime. This cloud screening procedure consists of calculating moving averages of δAe(λ and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable δAe(λ and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16° N, 3.60° W, 680 m a.s.l.; South-East of Spain for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.

  20. Dynamical Boson Stars

    Directory of Open Access Journals (Sweden)

    Steven L. Liebling

    2012-05-01

    Full Text Available The idea of stable, localized bundles of energy has strong appeal as a model for particles. In the 1950s, John Wheeler envisioned such bundles as smooth configurations of electromagnetic energy that he called geons, but none were found. Instead, particle-like solutions were found in the late 1960s with the addition of a scalar field, and these were given the name boson stars. Since then, boson stars find use in a wide variety of models as sources of dark matter, as black hole mimickers, in simple models of binary systems, and as a tool in finding black holes in higher dimensions with only a single Killing vector. We discuss important varieties of boson stars, their dynamic properties, and some of their uses, concentrating on recent efforts.

  1. Giant star seismology

    CERN Document Server

    Hekker, S

    2016-01-01

    The internal properties of stars in the red-giant phase undergo significant changes on relatively short timescales. Long near-interrupted high-precision photometric timeseries observations from dedicated space missions such as CoRoT and Kepler have provided seismic inferences of the global and internal properties of a large number of evolved stars, including red giants. These inferences are confronted with predictions from theoretical models to improve our understanding of stellar structure and evolution. Our knowledge and understanding of red giants have indeed increased tremendously using these seismic inferences, and we anticipate that more information is still hidden in the data. Unraveling this will further improve our understanding of stellar evolution. This will also have significant impact on our knowledge of the Milky Way Galaxy as well as on exo-planet host stars. The latter is important for our understanding of the formation and structure of planetary systems.

  2. Carbon neutron star atmospheres

    CERN Document Server

    Suleimanov, V F; Pavlov, G G; Werner, K

    2013-01-01

    The accuracy of measuring the basic parameters of neutron stars is limited in particular by uncertainties in chemical composition of their atmospheres. For example, atmospheres of thermally - emitting neutron stars in supernova remnants might have exotic chemical compositions, and for one of them, the neutron star in CasA, a pure carbon atmosphere has recently been suggested by Ho & Heinke (2009). To test such a composition for other similar sources, a publicly available detailed grid of carbon model atmosphere spectra is needed. We have computed such a grid using the standard LTE approximation and assuming that the magnetic field does not exceed 10^8 G. The opacities and pressure ionization effects are calculated using the Opacity Project approach. We describe the properties of our models and investigate the impact of the adopted assumptions and approximations on the emergent spectra.

  3. Atomic diffusion in stars

    CERN Document Server

    Michaud, Georges; Richer, Jacques

    2015-01-01

    This book gives an overview of atomic diffusion, a fundamental physical process, as applied to all types of stars, from the main sequence to neutron stars. The superficial abundances of stars as well as their evolution can be significantly affected. The authors show where atomic diffusion plays an essential role and how it can be implemented in modelling.  In Part I, the authors describe the tools that are required to include atomic diffusion in models of stellar interiors and atmospheres. An important role is played by the gradient of partial radiative pressure, or radiative acceleration, which is usually neglected in stellar evolution. In Part II, the authors systematically review the contribution of atomic diffusion to each evolutionary step. The dominant effects of atomic diffusion are accompanied by more subtle effects on a large number of structural properties throughout evolution. One of the goals of this book is to provide the means for the astrophysicist or graduate student to evaluate the importanc...

  4. Collapse of axion stars

    Science.gov (United States)

    Eby, Joshua; Leembruggen, Madelyn; Suranyi, Peter; Wijewardhana, L. C. R.

    2016-12-01

    Axion stars, gravitationally bound states of low-energy axion particles, have a maximum mass allowed by gravitational stability. Weakly bound states obtaining this maximum mass have sufficiently large radii such that they are dilute, and as a result, they are well described by a leading-order expansion of the axion potential. Heavier states are susceptible to gravitational collapse. Inclusion of higher-order interactions, present in the full potential, can give qualitatively different results in the analysis of collapsing heavy states, as compared to the leading-order expansion. In this work, we find that collapsing axion stars are stabilized by repulsive interactions present in the full potential, providing evidence that such objects do not form black holes. In the last moments of collapse, the binding energy of the axion star grows rapidly, and we provide evidence that a large amount of its energy is lost through rapid emission of relativistic axions.

  5. Uniformly rotating neutron stars

    CERN Document Server

    Boshkayev, Kuantay

    2016-01-01

    In this chapter we review the recent results on the equilibrium configurations of static and uniformly rotating neutron stars within the Hartle formalism. We start from the Einstein-Maxwell-Thomas-Fermi equations formulated and extended by Belvedere et al. (2012, 2014). We demonstrate how to conduct numerical integration of these equations for different central densities ${\\it \\rho}_c$ and angular velocities $\\Omega$ and compute the static $M^{stat}$ and rotating $M^{rot}$ masses, polar $R_p$ and equatorial $R_{\\rm eq}$ radii, eccentricity $\\epsilon$, moment of inertia $I$, angular momentum $J$, as well as the quadrupole moment $Q$ of the rotating configurations. In order to fulfill the stability criteria of rotating neutron stars we take into considerations the Keplerian mass-shedding limit and the axisymmetric secular instability. Furthermore, we construct the novel mass-radius relations, calculate the maximum mass and minimum rotation periods (maximum frequencies) of neutron stars. Eventually, we compare a...

  6. Structure of Herbig AeBe disks at the milliarcsecond scale . A statistical survey in the H band using PIONIER-VLTI

    Science.gov (United States)

    Lazareff, B.; Berger, J.-P.; Kluska, J.; Le Bouquin, J.-B.; Benisty, M.; Malbet, F.; Koen, C.; Pinte, C.; Thi, W.-F.; Absil, O.; Baron, F.; Delboulbé, A.; Duvert, G.; Isella, A.; Jocou, L.; Juhasz, A.; Kraus, S.; Lachaume, R.; Ménard, F.; Millan-Gabet, R.; Monnier, J. D.; Moulin, T.; Perraut, K.; Rochat, S.; Soulez, F.; Tallon, M.; Thiébaut, E.; Traub, W.; Zins, G.

    2017-03-01

    Context. It is now generally accepted that the near-infrared excess of Herbig AeBe stars originates in the dust of a circumstellar disk. Aims: The aims of this article are to infer the radial and vertical structure of these disks at scales of order 1 au, and the properties of the dust grains. Methods: The program objects (51 in total) were observed with the H-band (1.6 μm) PIONIER/VLTI interferometer. The largest baselines allowed us to resolve (at least partially) structures of a few tenths of an au at typical distances of a few hundred parsecs. Dedicated UBVRIJHK photometric measurements were also obtained. Spectral and 2D geometrical parameters are extracted via fits of a few simple models: ellipsoids and broadened rings with azimuthal modulation. Model bias is mitigated by parallel fits of physical disk models. Sample statistics were evaluated against similar statistics for the physical disk models to infer properties of the sample objects as a group. Results: We find that dust at the inner rim of the disk has a sublimation temperature Tsub ≈ 1800 K. A ring morphology is confirmed for approximately half the resolved objects; these rings are wide δr/r ≥ 0.5. A wide ring favors a rim that, on the star-facing side, looks more like a knife edge than a doughnut. The data are also compatible with the combination of a narrow ring and an inner disk of unspecified nature inside the dust sublimation radius. The disk inner part has a thickness z/r ≈ 0.2, flaring to z/r ≈ 0.5 in the outer part. We confirm the known luminosity-radius relation; a simple physical model is consistent with both the mean luminosity-radius relation and the ring relative width; however, a significant spread around the mean relation is present. In some of the objects we find a halo component, fully resolved at the shortest interferometer spacing, that is related to the HAeBe class. Full Tables B1-B3, as well as results of other parametric fits, are only available at the CDS via anonymous

  7. General Relativity&Compact Stars

    Energy Technology Data Exchange (ETDEWEB)

    Glendenning, Norman K.

    2005-08-16

    Compact stars--broadly grouped as neutron stars and white dwarfs--are the ashes of luminous stars. One or the other is the fate that awaits the cores of most stars after a lifetime of tens to thousands of millions of years. Whichever of these objects is formed at the end of the life of a particular luminous star, the compact object will live in many respects unchanged from the state in which it was formed. Neutron stars themselves can take several forms--hyperon, hybrid, or strange quark star. Likewise white dwarfs take different forms though only in the dominant nuclear species. A black hole is probably the fate of the most massive stars, an inaccessible region of spacetime into which the entire star, ashes and all, falls at the end of the luminous phase. Neutron stars are the smallest, densest stars known. Like all stars, neutron stars rotate--some as many as a few hundred times a second. A star rotating at such a rate will experience an enormous centrifugal force that must be balanced by gravity or else it will be ripped apart. The balance of the two forces informs us of the lower limit on the stellar density. Neutron stars are 10{sup 14} times denser than Earth. Some neutron stars are in binary orbit with a companion. Application of orbital mechanics allows an assessment of masses in some cases. The mass of a neutron star is typically 1.5 solar masses. They can therefore infer their radii: about ten kilometers. Into such a small object, the entire mass of our sun and more, is compressed.

  8. Pulsating Star Mystery Solved

    Science.gov (United States)

    2010-11-01

    By discovering the first double star where a pulsating Cepheid variable and another star pass in front of one another, an international team of astronomers has solved a decades-old mystery. The rare alignment of the orbits of the two stars in the double star system has allowed a measurement of the Cepheid mass with unprecedented accuracy. Up to now astronomers had two incompatible theoretical predictions of Cepheid masses. The new result shows that the prediction from stellar pulsation theory is spot on, while the prediction from stellar evolution theory is at odds with the new observations. The new results, from a team led by Grzegorz Pietrzyński (Universidad de Concepción, Chile, Obserwatorium Astronomiczne Uniwersytetu Warszawskiego, Poland), appear in the 25 November 2010 edition of the journal Nature. Grzegorz Pietrzyński introduces this remarkable result: "By using the HARPS instrument on the 3.6-metre telescope at ESO's La Silla Observatory in Chile, along with other telescopes, we have measured the mass of a Cepheid with an accuracy far greater than any earlier estimates. This new result allows us to immediately see which of the two competing theories predicting the masses of Cepheids is correct." Classical Cepheid Variables, usually called just Cepheids, are unstable stars that are larger and much brighter than the Sun [1]. They expand and contract in a regular way, taking anything from a few days to months to complete the cycle. The time taken to brighten and grow fainter again is longer for stars that are more luminous and shorter for the dimmer ones. This remarkably precise relationship makes the study of Cepheids one of the most effective ways to measure the distances to nearby galaxies and from there to map out the scale of the whole Universe [2]. Unfortunately, despite their importance, Cepheids are not fully understood. Predictions of their masses derived from the theory of pulsating stars are 20-30% less than predictions from the theory of the

  9. A search for nearby young stars among the flare stars

    CERN Document Server

    König, B; Hambaryan, V; Neuh\\"auser, Ralph; Hambaryan, Valeri

    2001-01-01

    Flare stars were discovered in the late 1940s in the solar vicinity and were named UV Cet-type variables (classical FSs). Among the FSs within 100 pc we search for young stars. For the search we take spectra with sufficient resolution to resolve Lithium at 6707 \\AA and Calcium at 6718 \\AA of all the stars. The real young stars are prime targets for the search of extra-solar planets by direct imaging.

  10. Really Hot Stars

    Science.gov (United States)

    2003-04-01

    Spectacular VLT Photos Unveil Mysterious Nebulae Summary Quite a few of the most beautiful objects in the Universe are still shrouded in mystery. Even though most of the nebulae of gas and dust in our vicinity are now rather well understood, there are some which continue to puzzle astronomers. This is the case of a small number of unusual nebulae that appear to be the subject of strong heating - in astronomical terminology, they present an amazingly "high degree of excitation". This is because they contain significant amounts of ions, i.e., atoms that have lost one or more of their electrons. Depending on the atoms involved and the number of electrons lost, this process bears witness to the strength of the radiation or to the impact of energetic particles. But what are the sources of that excitation? Could it be energetic stars or perhaps some kind of exotic objects inside these nebulae? How do these peculiar objects fit into the current picture of universal evolution? New observations of a number of such unusual nebulae have recently been obtained with the Very Large Telescope (VLT) at the ESO Paranal Observatory (Chile). In a dedicated search for the origin of their individual characteristics, a team of astronomers - mostly from the Institute of Astrophysics & Geophysics in Liège (Belgium) [1] - have secured the first detailed, highly revealing images of four highly ionized nebulae in the Magellanic Clouds, two small satellite galaxies of our home galaxy, the Milky Way, only a few hundred thousand light-years away. In three nebulae, they succeeded in identifying the sources of energetic radiation and to eludicate their exceptional properties: some of the hottest, most massive stars ever seen, some of which are double. With masses of more than 20 times that of the Sun and surface temperatures above 90 000 degrees, these stars are truly extreme. PR Photo 09a/03: Nebula around the hot star AB7 in the SMC. PR Photo 09b/03: Nebula near the hot Wolf-Rayet star BAT99

  11. Atmospheres around Neutron Stars

    Science.gov (United States)

    Fryer, Chris L.; Benz, Willy

    1994-12-01

    Interest in the behavior of atmospheres around neutron stars has grown astronomically in the past few years. Some of this interest arrived in the wake of the explosion of Supernova 1987A and its elusive remnant; spawning renewed interest in a method to insure material ``fall-back'' onto the adolescent neutron star in an effort to transform it into a silent black hole. However, the bulk of the activity with atmospheres around neutron stars is concentrated in stellar models with neutron star, rather than white dwarf, cores; otherwise known as Thorne-Zytkow objects. First a mere seed in the imagination of theorists, Thorne-Zytkow objects have grown into an observational reality with an ever-increasing list of formation scenarios and observational prospects. Unfortunately, the analytic work of Chevalier on supernova fall-back implies that, except for a few cases, the stellar simulations of Thorne-Zytkow objects are missing an important aspect of physics: neutrinos. Neutrino cooling removes the pressure support of these atmospheres, allowing accretion beyond the canonical Eddington rate for these objects. We present here the results of detailed hydrodynamical simulations in one and two dimensions with the additional physical effects of neutrinos, advanced equations of state, and relativity over a range of parameters for our atmosphere including entropy and chemical composition as well as a range in the neutron star size. In agreement with Chevalier, we find, under the current list of formation scenarios, that the creature envisioned by Thorne and Zytkow will not survive the enormous appetite of a neutron star. However, neutrino heating (a physical effect not considered in Chevalier's analysis) can play an important role in creating instabilities in some formation schemes, leading to an expulsion of matter rather than rapid accretion. By placing scrutiny upon the formation methods, we can determine the observational prospects for each.

  12. Morphodynamics of star dunes

    Science.gov (United States)

    Zhang, D.; Narteau, C.; Rozier, O.; Courrech du Pont, S.

    2012-04-01

    Star dunes are among the biggest and the most impressive dunes in Earth sand seas. Nonetheless, they remain poorly studied, probably because of their apparent complexity. They are massive pyramidal dunes with interlaced arms whose slip faces are oriented in various directions. Being large, they can integrate wind properties over a wide range of time scales. Thus, they are observed for wind regimes with multiple directions, and may result from the amalgamation of dunes or from the development of arms on a well-established dune pattern. In both cases, the roles of wind directional variability and secondary flow have been emphasized but not precisely quantified. Here, we report simulations where the star dune shape results from a a combination of longitudinal dunes, which form the star dune arms. These arms may radiate and so interact with the other dunes in the field. This mass exchange, controlled by the morphodynamics of star dunes arms, must play an important role in the large-scale arrangement of star dunes networks. We first demonstrate that star dune arms orientation maximizes the flux in the direction of crests. This is opposed to the usually admit dunes orientation, which maximizes the sediment transport perpendicular to the crest. Indeed, depending on sand availability, dunes development results from the growth of a wave on a sand bed or from a net transport of sediment, which grows and extends an isolated longitudinal dune over a non-erodible soil. These two different mechanisms lead to two different modes of crests orientation. Then, we show that the propagating arms reach a stationary state characterized by constant width, height and growth rate. These are controlled by the frequency at which the wind changes direction. Arm width and height increase, whereas the propagation speed decreases with a decreasing frequency. These morphodynamics properties are helpful to assess from pattern observation the variability of wind directionality over several time

  13. Weighing the Smallest Stars

    Science.gov (United States)

    2005-01-01

    VLT Finds Young, Very Low Mass Objects Are Twice As Heavy As Predicted Summary Thanks to the powerful new high-contrast camera installed at the Very Large Telescope, photos have been obtained of a low-mass companion very close to a star. This has allowed astronomers to measure directly the mass of a young, very low mass object for the first time. The object, more than 100 times fainter than its host star, is still 93 times as massive as Jupiter. And it appears to be almost twice as heavy as theory predicts it to be. This discovery therefore suggests that, due to errors in the models, astronomers may have overestimated the number of young "brown dwarfs" and "free floating" extrasolar planets. PR Photo 03/05: Near-infrared image of AB Doradus A and its companion (NACO SDI/VLT) A winning combination A star can be characterised by many parameters. But one is of uttermost importance: its mass. It is the mass of a star that will decide its fate. It is thus no surprise that astronomers are keen to obtain a precise measure of this parameter. This is however not an easy task, especially for the least massive ones, those at the border between stars and brown dwarf objects. Brown dwarfs, or "failed stars", are objects which are up to 75 times more massive than Jupiter, too small for major nuclear fusion processes to have ignited in its interior. To determine the mass of a star, astronomers generally look at the motion of stars in a binary system. And then apply the same method that allows determining the mass of the Earth, knowing the distance of the Moon and the time it takes for its satellite to complete one full orbit (the so-called "Kepler's Third Law"). In the same way, they have also measured the mass of the Sun by knowing the Earth-Sun distance and the time - one year - it takes our planet to make a tour around the Sun. The problem with low-mass objects is that they are very faint and will often be hidden in the glare of the brighter star they orbit, also when viewed

  14. Genetic characterization of three CRF01_AE full-length HIV type 1 sequences from Fujian Province, China

    Institute of Scientific and Technical Information of China (English)

    HUANG Hai-long; YAN Yan-sheng; YAN Ping-ping; ZHENG Jian; WU Shou-li; CHENG Ge; LIN Xun; ZHENG Wu-xiong; XIE Mei-rong; ZHANG Jian-ming

    2006-01-01

    Background One of the major characteristics of the human immunodeficiency virus type 1 (HIV-1) is its unusually high degree of genetic variability, which involves in genetic diagnosis, subtyping, vaccine design, and epidemiology. HIV-1 CRF01_AE is a main prevalent HIV-1 recombinant strain in China. In this study, three full-length CRF01_AE genomes from Fujian Province, China were cloned, sequenced, and analyzed; and the further genetic diversity defining and epidemiologic analysis were carried out.Methods Proviral DNA was extracted from non-cultured peripheral blood mononuclear cells, the near full-length HIV-1 genome was amplified and the PCR products were cloned into Pcr-XL-TOPO vector and sequenced. 5'-long terminal repeat (LTR) and 3'-LTRs were amplified by additional independent PCR and cloned into Pmd18t vector. Gene-based phylogenic tree was constructed and genetic distances were calculated by MEGA 3.1. Simplot was used for Bootscan analysis.Results The phylogeny and genetic distance analysis of the three near full-length sequences confirmed that these three samples clustered with CRF01_AE isolates, more close to Thailand CRF01_AE strain CM240, and were distantly related to African CRF01_AE strain 90CF402. Analysis of their genomic organization revealed the presence of nine potential open reading frames. There were no major deletions, rearrangements, or insertions in the three sequences, but an in-frame stop codon was found in tat gene of Fj051. LTRs of the three sequences contained a few nucleotides mutation. We did not find new mosaic recombinant in the three sequences. The V3 motif was GPGQ in all the three sequences, and there were only few amino acids differences in all three V3 loop sequences.Conclusion This report reveals the background of the three full-length CRF01_AE genomes, the most dominantly circulating HIV-1 strain in Fujian Province, China. The work is essential for the design and development of an effective AIDS vaccine for the region.

  15. A Real Shooting Star

    Science.gov (United States)

    2007-01-01

    [figure removed for brevity, see original site] Click on the image for movie of A Real Shooting Star This artist's animation illustrates a star flying through our galaxy at supersonic speeds, leaving a 13-light-year-long trail of glowing material in its wake. The star, named Mira (pronounced my-rah) after the latin word for 'wonderful,' sheds material that will be recycled into new stars, planets and possibly even life. NASA's Galaxy Evolution Explorer discovered the long trail of material behind Mira during its survey of the entire sky in ultraviolet light. The animation begins by showing a close-up of Mira -- a red-giant star near the end of its life. Red giants are red in color and extremely bloated; for example, if a red giant were to replace our sun, it would engulf everything out to the orbit of Mars. They constantly blow off gas and dust in the form of stellar winds, supplying the galaxy with molecules, such as oxygen and carbon, that will make their way into new solar systems. Our sun will mature into a red giant in about 5 billion years. As the animation pulls out, we can see the enormous trail of material deposited behind Mira as it hurls along between the stars. Like a boat traveling through water, a bow shock, or build up of gas, forms ahead of the star in the direction of its motion. Gas in the bow shock is heated and then mixes with the cool hydrogen gas in the wind that is blowing off Mira. This heated hydrogen gas then flows around behind the star, forming a turbulent wake. Why does the trailing hydrogen gas glow in ultraviolet light? When it is heated, it transitions into a higher-energy state, which then loses energy by emitting ultraviolet light - a process known as fluorescence. Finally, the artist's rendering gives way to the actual ultraviolet image taken by the Galaxy Evolution Explorer Mira is located 350 light-years from Earth in the constellation Cetus, otherwise known as the whale. Coincidentally, Mira and its 'whale of a tail' can be

  16. Synthetic guide star generation

    Science.gov (United States)

    Payne, Stephen A [Castro Valley, CA; Page, Ralph H [Castro Valley, CA; Ebbers, Christopher A [Livermore, CA; Beach, Raymond J [Livermore, CA

    2008-06-10

    A system for assisting in observing a celestial object and providing synthetic guide star generation. A lasing system provides radiation at a frequency at or near 938 nm and radiation at a frequency at or near 1583 nm. The lasing system includes a fiber laser operating between 880 nm and 960 nm and a fiber laser operating between 1524 nm and 1650 nm. A frequency-conversion system mixes the radiation and generates light at a frequency at or near 589 nm. A system directs the light at a frequency at or near 589 nm toward the celestial object and provides synthetic guide star generation.

  17. The physics of stars

    CERN Document Server

    Phillips, A C

    1999-01-01

    The Physics of Stars, Second Edition, is a concise introduction to the properties of stellar interiors and consequently the structure and evolution of stars. Strongly emphasising the basic physics, simple and uncomplicated theoretical models are used to illustrate clearly the connections between fundamental physics and stellar properties. This text does not intend to be encyclopaedic, rather it tends to focus on the most interesting and important aspects of stellar structure, evolution and nucleosynthesis. In the Second Edition, a new chapter on Helioseismology has been added, along with a list

  18. The formation of stars

    CERN Document Server

    Stahler, Steven W

    2008-01-01

    This book is a comprehensive treatment of star formation, one of the most active fields of modern astronomy. The reader is guided through the subject in a logically compelling manner. Starting from a general description of stars and interstellar clouds, the authors delineate the earliest phases of stellar evolution. They discuss formation activity not only in the Milky Way, but also in other galaxies, both now and in the remote past. Theory and observation are thoroughly integrated, with the aid of numerous figures and images. In summary, this volume is an invaluable resource, both as a text f

  19. Composting: a solution for reduction of environmental impacts caused by waste disposal pruning of AES Eletropaulo concession area; Compostagem: a solucao para diminuicao dos impactos ambientais causados pela destinacao dos residuos de poda da area de concessao da AES Eletropaulo

    Energy Technology Data Exchange (ETDEWEB)

    Cortez, C.L.; Coelho, S.T.; Grisoli, R.P.S.; Gavioli, F.; Gobatto, D. [Centro Nacional de Referencia em Biomassa (CENBIO), Sao Paulo, SP (Brazil); Carmelo, S. [AES Eletropaulo, Sao Paulo, SP (Brazil)

    2008-07-01

    Considering environmental issues, the increasing production of solid residues is important due to scarcity of methods and solution for their management. This article presents a project that aims to research the impacts caused by residues of urban pruning generated by the AES Eletropaulo Energy Distribution Company, and also to develop the standardization of this residues composting, finalizing the management of this operation. The obtained results refer to the research done in the areas under AES concession, regarding the collection and the destination of these residues. It has been observed that 50% of the municipalities dispose their residues in dumps or sanitary landfills, while only 8% compost them. Based on environmental and social responsibility concepts, it is expected that the conclusion of this work can assist the civil, public and private sectors to contribute to the sustainable development. (author)

  20. ENERGY STAR Certified Imaging Equipment

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 2.0 ENERGY STAR Program Requirements for Imaging Equipment that are effective as of...